Video Freezing When Choosing Blur or Virtual Background

My video freezes when I try to make a virtual background change in a meeting in ZOOM.
When I select NONE my video comes back. I am using Ubuntu 20.04 OS. I have friends using ubuntu but don't have that problem.
When I was using windows I hadn't that problem.
To fix the problem: 1. I joined a meeting from my mobile phone. I was able to change the virtual background from my mobile phone.. 2. I checked the Settings>meetings section in the Zoom administrator settings. "virtual background" button was on. 3. Zoom app is up to date.
4. I watched a lot of videos on youtube and applied but the result was same.