I don't use Caséta dimmers so can't check this for sure, but I'd guess that it probably only sends the new level to Hubitat after it's done dimming, not during. Maybe someone who uses it knows if there are any other options (I'm not aware of any).
I should share with you my favorite solution, which also works with Caséta: Pico Remotes. I use these to dim (or turn on/off, change color temperature, etc.) lots of Hue lights around my house, among other uses, and they're great! However, there may be some delay going from a Pico to Hubitat back to the Caséta dimmer, i.e., Lutron-to-Lutron with the hub as an intermediary: Radio RA2 /Hubitat best practices form the start - #9 by bravenel. But you should be able to set up the Pico in Caséta to control the dimmer directly, all via Lutron, then save the Hue part for Hubitat. However, that might be awkward unless you always use the Pico instead of the actual Caséta dimmer. But, again, maybe someone else will have other ideas.
