I am having this problem with LibreOffice Writer on Linux Mint.
Strangely, actual web URL links work fine, as do links to files on the same Linux box, however, links to Zotero items do not. They do not become active links in the Writer document, unlike the other two types of link.
The Zotero “select items link” has been working until today and links still open on LibreOffice on my Mac, although I now need to format the links manually. Prior to 6.4 the links were recognized by Writer automatically.
This is an example of an actual link to a Zotero item:
The Autocorrect setting does not solve the problem. I updated LO on Linux to the Fresh version and that did not solve the problem either.
LibreOffice version on Linux: Version: 18.104.22.168
Build ID: 3d775be2011f3886db32dfd395a6a6d1ca2630ff
Linux Mint 19.3 Tricia
Kernel: Linux 5.3.0-53-generic
The LibreOffice on Mac which DOES open the Zotero item links is