Problems with Libreoffice -Languague tool can not be started

[gabix]

I confirm that there might be a problem. See this thread:

Is my installation correct?

In LibreOffice version 6.4.6.2 I installed LanguageTool version 5.1.3. This seems the last user version. The newer versions seems to be developer version. I tried that before, it failed, and now I use 5.1.3. My OS is Ubuntu 20.04. The installation seems to be ok. In LibreOffice Menu → Tools → Extension manager → I see LanguageTool-5.1.3.oxt without an error message. But I do not see a window with 4 LanguageTool icons to check my text. To verify I copied the text, with spelling errors, in the D…

As I reported there, LT 4.1 and 5.1.3 work fine, while 5.2.2 as well as the latest snapshots of 20200202 and 20200203 do not, even repeated words are not detected (tested on Dutch, English and Russian samples).

Also tested with Apache OpenOffice 4.2.0 (it is an old development build, just for clarity). The same situation: LT 5.1.3 works, 5.2.2 and the latest snapshots do not work.