A). Check whether your account and password are correct. You can make use of 'Forget Password', in case required
B). App attempts to syncs data when logout is triggered. Make sure your mobile device is in network with WiFi or mobile data network for data to be securely backed up on the PLAY servers.
C). Clear cache data for PLAYFIT app and try again.
D). You can try Force Stop the App and try logging again.
E). Restart your mobile device (at times the Bluetooth of the mobile device get stalled).