I just patched my install with #396. I noticed that while I'm in heat mode any attempt to change temperature, either via UI or service call, fails. When I switch to cool mode, the temperature setting works as expected.
I suspect that wWe need to use ERD "Target Heating Temperature" (0x7002) instead of "Target Cooling Temperature" (0x7003) while in heat mode.
Note that as far as I can tell, the unit retains a single temperature for both modes - it doesn't remember the old "cool" temperature when you switch back to cool mode 🙄.