I've tried to reproduce this by unplugging my Ethernet cable and all aerial cables to tuners, then letting the box run for 50 mins (to ensure that an ntpdate-sync ran). This was ~20:20 to ~21:10.
The time progressed as normal through this.
My log shows:
whereas yours showed that ntpdate-sync had reset the time to 0 (or at least <= 10000).< 1968.336> [Console] finished: /usr/bin/ntpdate-sync
< 1968.337> [NetworkTime] setting E2 time: 1562787745.97
< 1968.339> [StbHardware] Set RTC to Wed 10 Jul 2019 20:42 (rtc_offset = 3600 sec.)
I can't see why it would do that on one system but not on another.