LT in LibreOffice doesn't find all English errors?

LT in LibreOffice suddenly(?) doesn’t seem to detect English errors based on grammar.xml anymore. Can somebody confirm that only the first error is found in this example document?

test-grammar-xml.odt (11.3 KB)

This is what it looks like for me:

Bildschirmfoto von 2020-07-05 17-31-18

I’m testing with LibreOffice 6.3.4.2.

Here it works okay with the latest LibreOffice 6.4.4 and the nightly .oxt

It works with LibreOffice 6.3.4.2 and the current nightly LanguageTool.