I agree, this is a PITA and it works just fine in X-Plane 11 but not in MSFS 2020.
Unless MSFS installs some kind of repeat on the button I may just use the Trim wheel up down for gear up/down and use the grey switch I used for gear as my trim up down, The other one I use for flaps up down.
If anyone finds a better answer to make this trim wheel work let us know.