Unfortunately we haven’t been able to pin down the cause for this. In the latest Android version, 1.21.17 (484), we added more code around this area of the app for debugging, which should give us more insight into what the app is doing when this happens. So once you update to that version of the app, please send us log files if you see this happen again.
To send log files, go to the About tab in the app and tap three times on the version number. You will then have the option to email the log files to us.