BTW, as a test, I disabled app nap in the applications info window. I left PM5 open when I left the studio at 8:30 and just got back about 4 hours later. It didn't hang!
As an interim solution, this could help others.
Log file attached. PM5 wasn't stuck at the time I generated it. In fact, I probably would not have been able to generate the log file when the app was in that state anyway.
Matthew
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