That's very odd that the problem returned. So you opened the same project and the same map, and the problem persists? Had you made any other changes to the map or the data in the map?
On my end, I can't reproduce the problem after closing out of Pro and restarting the computer, and then reopening the same project to the same map.
That's the thing with bugs, however, sometimes they cause unexpected behavior like this. Now that it is reported to the development teams, they can look into it further, and hopefully have a fix.
The good news is: I can't reproduce the bug in the latest (unreleased) build of ArcGIS Pro.
