Manager window rendering issue

hello lubos.
in Windows 10 x64 build 19043 there is an issue with Manager window.
when you switch between applications and return to Manager, the window is displayed blank.
if we minimize and restore the window it returns to normal state. i am not sure what is causing the issue.
i am on version 21.9.26 now. i had experienced this issue even on 21.9.10 which was my first update after few months from 21.1.14. the version 21.1.14 did not have any such issues.

below is a screenshot when you run the mouse over Manager window.

i would like to add that the issue is not related to any particular data files.
@lubos can you please check this as it is very annoying when there is a constant need to switch between other programs during double checking the data from other sources.