I've found another issue (perhaps its related to the same issue I'm seeing here: ) having to do with grouping of columns in grids that have formula columns. Basically whenever a grid (with a formula column) is grouped by a  non-formula column and then refreshed, the values in the formula column somehow disappear. I've attached a sample project. To reproduce the issue:

1) Run the project and resize the window so all 3 columns are visible

2) Group by one of the non-formula columns

3) Click in the grouping header area (this is a quick/dirty way that I got the 'refresh' functionality for the datasource in there)

Notice that now after expanding one of the groups, the formula column is totally blank.