Disappearing Tags

Hi -
I’ve just re-installed EMC (version 10.1.4588 (f11e2ab)) on a Windows 11 machine. This was after a power issue which caused me to delete all data from my pc and remove all the apps.

On re-installing EMC I note that some tags keep disappearing. I’ll tag the email and then leave EMC to do some work - when I come back the tag has gone from the email in question.

Anyone had a similar issue and how did you resolve it?
Thanks