With PSE 2020 when I attempt to use a brush like the Clone Stamp Tool the circle defining the area to be brushed quickly turns into a spinning icon without any periphery defining the area to be brushed. It’s difficult to remove unwanted items from images when you can’t tell where the brush action is taking place! I am using a 2017 iMac and upgraded to macOS Mojave on 12/14/2019. I installed PSE 2020 on 12/21/2019. From my research I understand that this problem surfaced with Adobe software when Mac users upgraded to Mojave back in 2018. I’m surprised that this issue is still hanging around! I’ll appreciate any information on how I can solve this aggravating problem.
I’m running Mojave on my Mac Book Pro and not seeing problems. Select your clone tool and try a tool reset. This often fixes problems. If that makes no difference go to preferences and click the button to reset pref settings on next launch. Quit the editor app and re-launch.
It could be a system memory issue. Are you running other apps at the same time. How much RAM is available ? Maybe you can post system specs. From the Editor menu go to:
Help >> System Info
Then copy & paste into a reply.
Thanks for letting us know. That will be helpful to others.