An automatic Logout on Checking In can be caused either due to expiry of a session or due to an Invalid Token error.
Expiry of session occurs when a Member has been Logged In from a device and has not Logged Out for a long time (say, for periods >14 days).
Invalid Token error occurs when a Member's credentials/Settings have been changed by a Super Admin/Admin and the Member is still Logged In with the old credentials/Settings.
Simply Login again with correct credentials and retry Checking In. The problem should stop.
There may also be an issue on some Android devices, specifically Xiaomi handsets. The problem should cease to persist if you try to Checkin again after Logging In. We have made fixes to minimize recurrence of the issue. But still, in very rare cases, some Android handsets may continue to have this problem.