Check the timestamps.
Yeah there are some errors in the logs very similar to https://www.traccar.org/forums/topic/timezone-aliases-loading-error-after-upgrading-from-traccar-512-to-61/page/2/
I have sent you an email @Anton, Hopefully this will help :-)
I meant position timestamps.
A really odd issue here.
Setup a new server and migrated across.
Upgraded to current 6.2 version.
A handful of devices show as online but never update their reported position.
If I delete and re add the device it will report again for a period of time before getting stuck again.
Any ideas?