This morning I've tested a regular ubuntu 20.04,
- freshly installed from iso image (in virtualbox) - just apt upgrade (where an update for libreoffice came in) - virtualbox guest additions
and the problem does _not_ occur on that.
So there's some relevant difference between Ubuntu 20.04 and Lubuntu 20.04.
This morning I've tested a regular ubuntu 20.04,
- freshly installed from iso image (in virtualbox)
- just apt upgrade (where an update for libreoffice came in)
- virtualbox guest additions
and the problem does _not_ occur on that.
So there's some relevant difference between Ubuntu 20.04 and Lubuntu 20.04.