I found out the problems in your sample code.

I can't exactly tell you the way to reproduce the problem because it is occurred randomly.

However, I tried to reproduce it, it's always occurred.

In your sample code, there are four groups.

I randomly expand and collapse four groups such as 1 expand, 2 expand, 1 collapse, 3 expand, 1 expand, 4 expand, 4 collapse, 2 collapse....

When I do these works repeatedly, suddenly the check box of 3 or 4 groups disappear and I can't recreate the check box in that groups.

I think that if you repeatedly do it 3~40 times, you can find out the problem.

p.s In this forum, I can not paste picture, which I captured, from the clipboard.

     Because of the secret policy, I can't upload files, such as .png or .jpg, from the computer.

Hello,

Thank you for the feedback.

I tried to reproduce this in the sample and I didn’t notice such thing. Can you be more specific with the steps to reproduce this? Can this be reproduced in my sample or you noticed it in your project? Does the amount of group by columns matter (does it happen when there is only one group by column, or you need more)? Does the speed with which you expand/collapse the groups matter? It would be really helpful, if you are able to make a small video demonstrating how to reproduce the issue.

I am looking forward to your reply.

Can you solve the problem that I found out?

I don't know why the check boxes suddenly disappeared.

I found out one more problem in your sample code.

When I repeatedly expand and collapse the groups, the check box of some groups suddenly disappear.

I cannot tell you the case exactly, but sometimes occurred.