Also running 20.04 LTS pre-release and seeing this problem with wired mouse. Haven't tried wireless mouse. Fresh install yesterday. Gnome 3.36.1. Haven't yet found a culprit but I do have Chrome installed. Seems to happen whether Chrome is running or not. Confirming that ALT-F2 and running the command "r" restarts the shell and the problem is gone for a while. Will continue to try to isolate and report back any useful findings.
Also running 20.04 LTS pre-release and seeing this problem with wired mouse. Haven't tried wireless mouse. Fresh install yesterday. Gnome 3.36.1. Haven't yet found a culprit but I do have Chrome installed. Seems to happen whether Chrome is running or not. Confirming that ALT-F2 and running the command "r" restarts the shell and the problem is gone for a while. Will continue to try to isolate and report back any useful findings.