Usinf CH yoke. Prior to update 5, I had button 10 configured to TOGGLE the Parking Brake either ON or OFF. If memory serves the Controller Option page even had some language indicating a “Toggle” of this parameter.
Since Update 5 the toggle option no longer exists and although I can RELEASE the Parking Brake I can no longer “SET” the Parking Brale - pessing & releasing the “10” key merely raises and lowers the handle or pulls/pushes the knob. I must click the mouse on the parking brake lever/knob to set it “ON”.
Try this to test:
Make a new yoke config, rename is test or sometime, change only the park brake to your button. Then test.
There have been some changes in msfs settings and
Some of your older configs need to be recreated from scratch. Do not copy the old one or just rename it. Create a new profile.