I'm back, with some interesting results.. :D
Yes there certainly does seem to be an issue with the Panasonic tuner/driver and COM 7 HD on 746mhz! Mine tunes OK but errors like crazy..
2019-05-06 05:53:32.623 subscription: 000C: "HTTP" subscribing to mux "746MHz", weight: 10, adapter: "Panasonic MN88472 #3 : DVB-T #0", network: "DVB-T - Sutton Coldfield", service: "Raw PID Subscription", hostname="192.168.1.253", client="VLC/3.0.3 LibVLC/3.0.3"
2019-05-06 05:53:34.161 tbl-base: pat: 746MHz in DVB-T - Sutton Coldfield: invalid checksum (len 1162, errors 1)
2019-05-06 05:53:37.339 tbl-base: nit: 746MHz in DVB-T - Sutton Coldfield: invalid checksum (len 89, errors 1)
2019-05-06 05:53:44.473 tbl-base: pat: 746MHz in DVB-T - Sutton Coldfield: invalid checksum (len 3, errors 6)
2019-05-06 05:53:50.307 tbl-base: nit: 746MHz in DVB-T - Sutton Coldfield: invalid checksum (len 89, errors 5)
2019-05-06 05:53:54.645 tbl-base: pat: 746MHz in DVB-T - Sutton Coldfield: invalid checksum (len 4, errors 9)
2019-05-06 05:54:07.182 tbl-eit: uk_freeview: 746MHz in DVB-T - Sutton Coldfield: invalid checksum (len 25, errors 1)
2019-05-06 05:54:08.694 tbl-base: pat: 746MHz in DVB-T - Sutton Coldfield: invalid checksum (len 3, errors 13)
but.. and here's the kicker.. after roughly 20-30 seconds of errors, they suddenly stop and VLC shows a picture!
!huh.png!
I'm only guessing here but I think the tuner is getting confused, especially seeing as other transmitters near have COM7 on 746 too. "SFN" issues maybe? Who knows!
Solutions:
* Horrible workaround, set a 247 hour recording so it's constantly tuned, saving the output to /dev/null
* Wait wait wait.. and wait for a picture LOL
It's a weird one, sorry I couldn't be of much help :(