Update Management Updates shows an empty list

My OMV server :
OMV version 4.31-1
Kernel 4.19.0-0.bpo.6-amd64

Problem:
In the OMV GUI the list Package Information in Update Management is empty. See attached picture.

Check for updates is working, no errors.
OMV can connect with internet.

Tried to solve the problem by:
- empty browser cache
- disable cookie filter and add blocker in browser
- reset OMV GUI to defaults
- restart OMV box.

Problem still not solved.
Before this happened, I was experimenting with the omv dnsmasq plug-in but I have switched it off and uninstalled it. Still no result.

Any idea how to fix this?

Is it?

There used to be a whole list of drivers etc., although they where not for my system.

So, now updates are only shown when applicable for my system and installed software?

I use no other method to check for updates, but since recently, I have a PC with Ubuntu and getting a bit familiar with the terminal, witch I could also use to access the OMV box command line.