My wife and I are zwift riders. We have 2 computers where we play from. We both use each computer from time to time. We have one iPhone were we installed the zwift mobile app. Sometimes my wife uses the mobile app with her account and sometimes I use it with mine.
Lately we have experience this problem where the mobile app controls the rider not currently logged into the mobile app. I log off the mobile app, reboot the phone, and start all over. The mobile app will pick up the rider that is logged onto the app for a few minutes and then switch to the other other.