Gateway occasionally sends wrong GPS time

Our Dragino DLOS8 Gateways occasionally transmits the timeSinceGpsEpoch parameter for some nodes. When it does, Chirpstack displays the transmission time as 1980-01-06 because the parameter is always set to a couple of seconds only. The system time of the gateways is fine and this happens sporadically for some nodes only, others are completely unaffected even at the same time.

Has anyone experienced something similar before or knows a possible fix?

Is it possible to disable the GPS time in Chirpstack itself?