How did you upgrade? If it was manual, make sure you didn't miss any app or driver files (or mismatch any). If HPM, try a repair.
Yes, by manually reverting the app and driver code or, more easily, by restoring a hub backup (you took one, right?) from before the upgrade. This is actually the only, or at least easiest, way to downgrade if you have the V2 API option enabled.
But this should work. The question is figuring out what went wrong on your hub.
Can you provide a screenshot of the changelog at the top of your CoCoHue app code under Apps Code? Also, any errors in Logs fom HPM during the upgrade?
When did you update? Your app code version is very old. The current versions would be 5.1 (different subversions depending on the individual app or driver). This could not have been the result of an HPM repair if the repair was successful.
Do you have multiple instances of the app installed? If so, it's possible HPM picked the wrong one.
The surest way to recover from this would be to restore a hub backup from a time when you know everything was working correctly, then upgrade again. But if you don't have duplicate app or driver files, you could also try a "manual" update. The easiest way to do that is to use download and import the bundle ZIP from the root of this repo: GitHub - HubitatCommunity/CoCoHue: Open-source community-created Hue Bridge integration for Hubitat. I'm not sure what is causing your HPM problem if that is what you are using, but it's definitely not getting the latest code if that is what you intended to upgrade. You could try an un-match and match up, maybe...
Yes, that is almost definitely the problem. HPM will only update the one it thinks it's in control of. I would remove any app and driver code you are not using (nothing under "Used by" on the "Apps Code" or "Drivers Code" page for those pieces of code; hopefully that leaves you with just one app and one of each driver). Doing a re-match-up in HPM should then make it find these and update them again. Alternatively, importing the bundle ZIP as I suggested above will update them all without HPM (more easily than doing so manually, which is possibly how this started in the first place?).
That being said, if the built-in integration meets your needs, that is certainly also a fine path.
I have now made a local backup
I think I will try to restore, just to see if I can repair, now the problem seems to be solved
Thank you very much for your time.