It should work with all supported browsers. We use Ubuntu 20.04 ourselves.
Even if you do not plan to use Chrome, can you please test with Chrome? This way we can learn if the issue is somehow browser specific. The challenge here is to recreate the problem, as we do not see it.
Also, I can give you access to one of our Ubuntu 20.04 test machines, so you can try to recreate the issue there. Once we see the issue, we can debug it. If this is an option for you, just email me.