This is a generic issue when a grid is using 'Group By' mode and the user opens the 'Column' panel to pick additional fields for the layout.
Steps to Reproduce:
Expected Results: The 'Column' panel should remain open until the user closes it.
Actual Results: The 'Column' panel automatically closes after checking the box to add just one field.
Workaround: None.
Release 16.1.2
DE69805
Fixed in Release 16.1.3 and in 16.1.2 Patch #1 (16.1.2.1)