my apologies for the delayed response. Crunch time on a project....
Windows 10 1903 build 18362.476
It's likely related to the other 5.985 report
https://forum.cockos.com/showthread.php?t=227204
or it was related to me turning off "run FX when stopped". which was the only preference I'd changed immediately prior to the update. If I can nail it down as something else I'll post again.