I have been controlling Zwift with TR workouts in the background. Is there a way to get my KICKR Climb to control Zwift grade simulation while continuing to use both platforms?
Not that I know. The Climb is linked to the Kickr. As such, the Climb will only react to the input from the controlling app.
So, since you have the “Controlled” option off in Z and TR is setting the resistance in ERG, or set to a Resistance % or Standard level (BLE only), there is no way for the Climb to get the grade info from Zwift. The only way for that to work would be if Z offered direct pairing to the Climb, but that’s not possible.
TR does offer some integration with the Climb, but I find it annoying and not beneficial.