I tried to do it as you did in your code, by moving the MaxWidth property setting outside of the InitializeLayout event and placing it in the Form_Load event, it didn't work for me.

private void ugResourcePlanning_InitializeLayout(object sender, InitializeLayoutEventArgs e)
{
    try
    {
        Infragistics.Win.BindableValueList bvl;
        string column;
        int parent = sd._parentBand;
        int headerPos = 0;
        
        // Default setup
        sf.ugDefaultSetup(e, true, true, Activation.AllowEdit);
        // Adds an empty row to add a new entry
        e.Layout.Override.AllowAddNew = AllowAddNew.TemplateOnBottom;
        e.Layout.AutoFitStyle = AutoFitStyle.None;
        
        // Define columns.
        //// ID
        //// ***HIDDEN***
        column = sd._fldResourceManagementID;
        e.Layout.Bands[parent].Columns[column].Hidden = true;
                
        //// Project
        //// Caption: "Project"
        column = sd._fldResourceManagementProject;
        bvl = new Infragistics.Win.BindableValueList(Prototype.ddlGetProject(), "", "Value", "ID", ugResourcePlanning);
        //bvl.SelectedIndex = 0;
        e.Layout.Bands[parent].Columns[column].Header.Caption = "Project";
        e.Layout.Bands[parent].Columns[column].Header.VisiblePosition = headerPos++;
        e.Layout.Bands[parent].Columns[column].Style = Infragistics.Win.UltraWinGrid.ColumnStyle.DropDownList;
        e.Layout.Bands[parent].Columns[column].Width = 130;
        e.Layout.Bands[parent].Columns[column].ValueList = bvl;
        
        
        //// Resource
        //// Caption: "Resource"
        column = sd._fldResourceManagementResource;
        bvl = new Infragistics.Win.BindableValueList(Prototype.ddlGetResource(), "", "Value", "ID", ugResourcePlanning);
        e.Layout.Bands[parent].Columns[column].Header.Caption = "Resource";
        e.Layout.Bands[parent].Columns[column].Header.VisiblePosition = headerPos++;
        e.Layout.Bands[parent].Columns[column].Style = Infragistics.Win.UltraWinGrid.ColumnStyle.DropDownList;
        e.Layout.Bands[parent].Columns[column].MinWidth = e.Layout.Bands[parent].Columns[column].MaxWidth = 100;
        e.Layout.Bands[parent].Columns[column].ValueList = bvl;

        //// Group
        //// Caption: "Group"
        column = sd._fldResourceManagementGroup;
        bvl = new Infragistics.Win.BindableValueList(Prototype.ddlGetGroup(), "", "Value", "ID", ugResourcePlanning);
        e.Layout.Bands[parent].Columns[column].Header.Caption = "Group";
        e.Layout.Bands[parent].Columns[column].Header.VisiblePosition = headerPos++;
        e.Layout.Bands[parent].Columns[column].Style = Infragistics.Win.UltraWinGrid.ColumnStyle.DropDownList;
        e.Layout.Bands[parent].Columns[column].MinWidth = e.Layout.Bands[parent].Columns[column].MaxWidth = 80;
        e.Layout.Bands[parent].Columns[column].ValueList = bvl;
        
        //// Month 1 Planned
        //// Caption: {Set by function}
        column = sd._fldResourceManagementPlanned1;
        e.Layout.Bands[parent].Columns[column].Header.Caption = "Planned";
        e.Layout.Bands[parent].Columns[column].Header.VisiblePosition = headerPos++;
        e.Layout.Bands[parent].Columns[column].CellActivation =
        (_employee.IsAdministrator || _employee.IsClientRelationsManager)
        ? Activation.AllowEdit
        : Activation.NoEdit;
        e.Layout.Bands[parent].Columns[column].Format = "##%";
        e.Layout.Bands[parent].Columns[column].MaxWidth = 50;
        e.Layout.Bands[parent].Columns[column].AllowGroupBy = Infragistics.Win.DefaultableBoolean.False;
        ugSetSummary(e, column, typeof(int), "Sum1P");
        
        //// Month 1 Allocated
        //// Caption: {Set by function}
        column = sd._fldResourceManagementAllocated1;
        e.Layout.Bands[parent].Columns[column].Header.Caption = "Allocated";
        e.Layout.Bands[parent].Columns[column].Header.VisiblePosition = headerPos++;
        e.Layout.Bands[parent].Columns[column].CellActivation =
        (_employee.IsAdministrator || _employee.IsProjectManager || _employee.IsResourceManager)
        ? Activation.AllowEdit
        : Activation.NoEdit;
        e.Layout.Bands[parent].Columns[column].Format = "##%";
        ugSetSummary(e, column, typeof(int), "Sum1A");
        
        // Rinse and repeat for 5 more months
    }
    Catch (Exception ex) { /* do stuff... */ }
}
    
    // Sets the Summary
public static void ugSetSummary(InitializeLayoutEventArgs e, string column, Type dataType, string SummaryKey,Infragistics.Win.HAlign align = Infragistics.Win.HAlign.Left)
{
        if (!e.Layout.Bands[sd._parentBand].Summaries.Exists(SummaryKey))
        {
            Type dt = e.Layout.Rows[0].Cells[column].Value.GetType();
            SummarySettings summary;
            summary = e.Layout.Bands[sd._parentBand].Summaries.Add(SummaryKey, SummaryType.Sum, e.Layout.Bands[sd._parentBand].Columns[column]);

            if (dt == typeof(double))
            {
                summary.DisplayFormat = "{0:F2}";
            }
            else if (dt == typeof(int))
            {
                summary.DisplayFormat = "{0:G}";
            }
            
            summary.Appearance.TextHAlign = align;
            e.Layout.Override.SummaryDisplayArea = SummaryDisplayAreas.Bottom;
    }
}
private void ugSetColumnGroups()
{
    UltraGridBand band = ugResourcePlanning.DisplayLayout.Bands[sd._parentBand];
    band.RowLayoutStyle = RowLayoutStyle.GroupLayout;
    
    UltraGridGroup firstGroup = band.Groups.Add("First Group", "");
    UltraGridGroup firstMonth = band.Groups.Add("Month 1", "July");
    UltraGridGroup firstMonth = band.Groups.Add("Month 1", "August");
    UltraGridGroup lastGroup = band.Groups.Add("Last Group", "");
    
    band.Columns[sd._fldResourceManagementProject].RowLayoutColumnInfo.ParentGroup = firstGroup;
    band.Columns[sd._fldResourceManagementResource].RowLayoutColumnInfo.ParentGroup = firstGroup;
    band.Columns[sd._fldResourceManagementGroup].RowLayoutColumnInfo.ParentGroup = firstGroup;
    band.Columns[sd._fldResourceManagementPlanned1].RowLayoutColumnInfo.ParentGroup = firstMonth;
    band.Columns[sd._fldResourceManagementCopy].RowLayoutColumnInfo.ParentGroup = lastGroup;
    
    firstMonth.Width = 100; 
}
private void FormManagement_Load(object sender, EventArgs e)
{
    try
    {
        // Setup UltraGrid
        ugResourcePlanning.DataSource = Prototype.ugGetResourcePlanning();
        ugSetColumnGroups();

        e.Layout.Bands[sd._parentBand].Columns[sd._fldResourceManagementPlanned1].MaxWidth = 50;
        e.Layout.Bands[sd._parentBand].Columns[sd._fldResourceManagementAllocated1].MaxWidth = 50;
        // Rinse and repeat for 5 more months.
    }
    catch (Exception ex) { sd.g_oErr.PersistDisplay(ex, true); }
}

Hi Robert, 

Are you having any trouble using my sample? If you are using a different version than Infragistics for Windows Forms 16.1 then please let me know and I can create the sample with that specific version.  

Please elaborate on the details of your Grid setup.  If you can reproduce this issue in a sample and send it to us that will help us in investigating why MaxWidth is not honored in your application. But if can’t then please give us more information on how to reproduce this issue. 

Sincerely,
Sahaja Kokkalagadda
Associate Software Developer