The LibreOffice Extension doesn't work for me.

Today I installed the LanguageTool LibreOffice extension (filename: LanguageTool-5.2.2.oxt). I am using the following configuration:
OS: CentOS Linux release 8.3.2011
LibreOffice version: 6.3.6.2
Java version: 1.8.0_275

The extension was installed without any error being reported. To test it, I typed a one-line document:
“This are a test test document.”

Nothing happened. I selected Tools / LanguageTool / Check Text, and still nothing happens.

I tried launching LibreOffice Writer from a terminal, and no errors are reported on the command line.

Any ideas how to get it working?

Dean

Have you checked these hints? LibreOffice/OpenOffice add-on : LanguageTool