I migrated my setup from ST last week, and as a heavy Hue user (I have 5 bridges) I encountered a couple bugs on the Hubitat integration.
I found the solutions buried in some old topics, so I decided to list them here so it's easier for anyone with the same issues to find them.
Issue: Can't add some light groups (dimmer and CT) to Google Home
Fix: The official Hue integration only has drivers for colour bulbs groups. Google home wants all the values to be filled in order to add them, even if unsupported by the lights. Therefore, all you need to do is click on set color in each of your light groups, so it populates the values.
Issue: Light group states not being refreshed
Fix: When setting up a Hue Bridge on Hubitat, even if you only intend to use Groups, make sure to add at least one individual bulb. Also, make sure to click on Hue Bridge Poll interval, and click done afterwards. This correctly sets the polling function.
I hope that helps other people like me.