It may just be the current build - I updated & then rebooted the PC, & Miranda kept crashing trying to load the profile - logs reckoned it was likely a MDBX issue. Pulled the entire install ( with profile ) out of my nightly backup from yesterday, started fine, checked the DB, compacted it, updated and got the same error - so either there's a bug in the DB handler somewhere or there's a problem migrating the DB. I seem to have two DB drivers installed, I don't know which order they try.
I'm prepared to just not update & wait for the next build, I can't spare the time to debug the issue right now.