I'm using TP Virtual with a custom FTMS device (which works fine with Zwift and Trainerroad) but it seems like TP Virtual is not requesting control and setting the target power as it should when I launch an ERG workout. I don't get any incoming commands on the Control Point char. If I then force a disconnect from my FTMS-device side, so that TP Virtual reconnects when already in the workout it starts by requesting control and then everything works fine.

Could you check if there's something in the logic when connecting that could cause it to never request control?