I have had this problem for some time. It started with 27 beta 2 but seemed to get fixed in beta 3. But from then on it all went back to the same problem I had encountered with beta 2 and its still here with the stable version 28.
I had posted a comment here re- beta 4, but have had no replies.
Please see the images attached. This happens when the print/export screen is up and we have a whiteout as shown. It also happens with the "Report Typo" screen. This happens whether using dark or light mode.
I would prefer to avoid an uninstall/reinstall, particularly, if that will not resolve the problem.
Print/Export screen of Sentence Diagram tool... & then the Report Typo Screen...

