I have cleared the cache on the Tiki and my browser.
I am proceeding cautiously and backing up my database before trying a reinstall of 12.6.
I will wait for a response before proceeding as I prefer to let softaculous do the work unless there is something I have to work around.
It gives me this message
As a security precaution, the Tiki Installer has been disabled. To re-enable the installer:
Use your file manager application to find the directory where you have unpacked your Tiki and remove the lock file which was created in the db folder.