Came across this bug 1892637 and did some testing on both releases and can confirm this. I cannot print anything from Libreoffice.
As a workaround I ran in terminal:
sudo apt install libreoffice-kf5
followed by:
sudo apt remove libreoffice-qt5
this needs further testing as there maybe adverse effects which I am not aware of.
See also earlier discussion on Discourse here .
Does it work as per Walter’s suggestion
That’s been my fall back in support questions on askubu & UF if I recall correctly. It’s what I’ve used too (though I rarely print)
Yes it works but it is not a permanent fix. You have to run it from the terminal every time you use Libre writer which is inconvenient for many users. I intend to test this further on various boxes/setups.
Anyone else interested in testing this is more than welcome. 
you can change the ENV variable in Session Config
Actually we should have changed it for 20.10, I forgot.
Thank you @hmollercl
Maybe we should include mention of that in final release notes as a work-around @kc2bez for groovy.
Yes thank you @hmollercl !
Tested and solved. However this also needs to be added to 20.04.1 as well as 20.10. @guiverc @kc2bez
20.04.1 is out already, 20.04.2 can still be changed.
I’m not sure forcing a change on everyone (ie. existing users with installed focal systems) is a great solution; I fear it’ll break some manual fixes/work-arounds people have already implemented so I’d suggest we concentrate on new releases, and deal with existing via support, posts etc.
A question, then answer on AskUbuntu for example (alas I’m probably the person for that). Maybe
I’d suggest a post here first, and I could use that as my basis for an Ask Ubuntu one, with link to here 
and something that can be used to refer users to whenever UF/askubu/other questions are noticed.
–
@Leok sorry I referenced a link you were no doubt fully aware of (even likely helped test!), I’d not noticed it was the same link you made reference to, so apologies.
Good suggestion and will do - 
I forgot to mention that this introduce a small bug in libreoffice which is that some movements/resizing of the window might cause window content freeze, which is solved by maximizing/unmaximizing it.
I haven’t had time to look if the bug exist and create it if not. If someone could it would be great. Here https://bugs.documentfoundation.org
@hmollercl
Thanks for the tip…I will test that as well and report back.
Hi, Is this what you are referring to? When I tried to fix this printing issue, I ended up with editing issues which I talk about in this post Libre Office Editing Problem
I haven’t “logged” the bug anywhere but here, I don’t know how, and no one else seemed interested anyway.
I haven’t tried the maximising/unmaximising fix either.
The other suggestion of removing libreoffice-qt5 and replacing it with libreoffice-kf5 doesn’t make sense to me because according to Muon package manager, one of the depends of libreoffice-kf5 is libreoffice-qt5, so how does it help by removing it?
This was just a suggestion that I stumbled onto and tested. I never recommended it as I stated it needed further testing. The reply by @hmollercl pointing out the need for the env variable in Session config appears to solve the problem. I am still testing this and will post my results in a separate post when finished.
Sorry for any confusion caused by my original post above.
Hi, I’m sorry if I implied you had caused any confusion, you hadn’t. I had seen the suggestion to replace libreoffice-qt5 with libreoffice-kf5 in another post, and it was by looking for it in Muon that I discovered the association, causing the confusion.
I’ve actually been wondering if we need both -qt5 and -kf5 installed to resolve the printing issue. Or would this not help at all? My understanding of this type of thing is non-existent so if I’m talking jibberish let me know 
This issue is due to bug in libreoffice-qt5.
To recorrect the issue uninstall it.
sudo apt remove libreoffice-qt5
After this restart the pc.
The problem will solve.