When I attempt to reconcile, I get the message "Another application is currently editing the version."
I have been editing and reconciled/posted this morning with no issues. This problem occurs intermittently, with no changes in program usage. It occurred a few weeks ago to me and is occurring again. A team mate has reported she now had the issue with her ArcGIS Pro.
Right now the solution has just been wait and see.
I'm using version ArcGIS Pro 2.8.3.