Just wanted to let you and anyone else fighting with this know: the issue is with the firmware Hubitat is using in their Z-Wave stick. I also assume its the same issue in their integrated solution in newer boxes; I have the same issue in both my EU C-5 boxes using the external stick, and both my EU C7:s using box-integrated Z-Wave.
How do I know? Well, after fighting with this for YEARS, on first Smartthings, and then three different Hubitat boxes Hubitat, I decided to start a Home Assistant instance on my Windows server and try to get that to work. And as soon as I did, it let me know that the firmware on the stick from Hubitat had severe known bugs, and needed an update. Which of course Hubitat never managed to tell me; neither in the user interface nor from support. I can only assume they don't have a clue...
The forware upgrade was not entirely painless, but that was just because I was stupid and decided to upgrade to the latest (stable) version instead of the recommended version, and downgrading was a pain in the #¤%.
But once the correct upgrade was in place, the warnings disappeared, and everything has been smooth sailing since. All my devices has now been migrated to Home Assistant, scenes and automations created, and everything works perfectly. Honestly, Home Assistant is just so much ahead of Hubitat in nearly everything that it is not even funny. HA is just as easy (although different...) to work with as long as you don't need to do anything super-complicated*), and driver support is unparallelled. I have some weird stuff that I never got to work on Hubitat, and in HA it just works. Amazing.
I still keep my Hubitat around, but just as a gateway to Google Home, because I'm to cheap to pay for the service in HA.
*) Just about everything that you can do on Hubitat can be done easily with HA. The complex stuff that really takes you into the dreaded .yaml config files is generally not possible with Hubitat anyway.