Ok, your issue is due to the below known bug.
Fatal error: Call to a member function get() on string in /components/com_comprofiler/plugin/user/plug_cbautoactions/models/activity.php on line 53
It's caused by custom CB Activity auto actions not completely migrating. The fix is to re-save those actions. I've re-saved the one action you have and confirmed working fine now. I've also added a bug ticket to track down why the CB Auto Actions migration is causing this.
forge.joomlapolis.com/issues/6586