The Word overlay on Desktop (Windows 11) often lose focus and does not come back by itself. I can get it back by switching windows back and forth.
Here’s a screen recording to illustrate the problem:

I post here because the LanguageTool support team never responded to my feedback.
Could be related to this (though in my case it happens even with single-page documents): Desktop app only corrects first 38 pages in Word
LanguageTool de* sktop version: 1.6.4.0
- Windows 11 Pro Version 24H2
- Microsoft Office LTSC Professional Plus 2021