It’s true, HALion is a little different because with Version 6 one got the option to keep it on a software licenser instead of on a dongle.
H5 and earlier ‘only’ work from a dongle, and can’t use the H6 key, be it on Dongle, or on a soft eLicenser.
The practice had been to contact Steinberg support and they’d send you a H5 ‘add on’ key for your dongle.
I think you need BOTH keys to be on the system to roll back…but the special key is the one that older version of HALion access to get permission to run. The H6 key can be on dongle, or on soft eLicenser.
It all worked out for me, but it’s been years back now. I sent the message to support at some point during a weekend, and got an add-on key from them on Monday.
I’d probably send another ticket just to see what happens. Never know. A different rep might answer it and know something “Adam” didn’t? Or maybe ‘access’ has been restored? Nothing to lose by trying.