On a suggestion from Helmut on my github issue, I’ve switched over to jdbc for MySQL binding. I just left the database ‘as-was’ and configured the jdbc driver to be backwards compatible. I did have to disable SSL in the command parameters:
url=jdbc:mysql://localhost:3306/OpenHAB?useSSL=false
All seems to be working now. It is a very strange thing indeed that it worked in M8 and not stable, and I do not like leaving this unanswered - however the fix, at this stage, is to move to the jdbc binding for MySQL and not use the MySQL Persistence binding.
Hope this helps.