Using a button mapped to CG Disabled (monitor) does get it to unmute for traffic while scan is on, but so far that's the only way I've been able to.
Monitor and Call Guard (disable) are a side issue and not adequately addressed in the help files. I did trial and error with various monitor and call guard settings to try to find what they actually did. I don’t remember the details of what I found so working from memory without any guarantees made or implied. It began with me trying to setup my VP like my KW NX5300 on P25 so I could unmute on any TG while Transmitting whatever TG outgoing I wanted. I wanted this to be on a per channel basis. I was not successful. My work around was to use a TG of “FFFF” (All call or Broadcast) which would unmute on any incoming TG and also on TX it would cause any receiving radio to unmute regardless of the TG it was using. On the NX I can set a channel to ignore incoming TG while respecting NAC.
On VP I have number 0 button mapped to Monitor. A momentary press caused radio to monitor (open squelch/noise) TX Channel. A long press gives me Squelch Override on RX Channel. I have another button mapped “Selective/Normal” where button press alternates between the two. On Normal it ignores TG but I cannot remember how it handles NAC, CC, or PL—regardless it is a global setting and not per channel. I believe Call Guard disable ignores everything but not positive. The per channel “Digital Squelch” ignores everything except the digital voice signal.
Having said all of that I don’t believe your problem is related to monitor per se. The only other squelch related settings I can find involve RSSI thresholds and can help efficiency with “Look Back” for priority channels during scan. To that end I would probably create a scan list without any Priority Channels in it to see what happens. If it works then I’d know something is wrong with priority settings involving look back times probably.
What kind of repeater is the system in question on?
MMDVM based repeaters are often not setup correctly (pulse width, band width, and other timing issues). My KW NX5300 is very sensitive to this on both DMR and P25 receive. My motorolas and other radios are NOT as selective on signal quality and have worked on mmdvm repeaters that my NX either won’t unmute reliably or at all. While I don’t know how much technology crossover there is between KW and EFJ (doesn’t seem to be a lot…) I would have suspicions about VP8000 also being picky about signal being in spec (not noticed so far by me). Tait radios like Motorola may be more tolerant of out of spec signals. The counterpoint is that your radio decodes when not scanning….no theory for this beyond look back timing for priority channels.
I have never noticed any issues when on a non mmdvm repeater and have also had good results on some mmdvm repeaters which were probably more carefully calibrated.
This is to say the repeater could be your problem.
Does your radio “Land” on active channel during scan and sit there for the duration of the transmission? I realize it is not unmuting but otherwise is the behavior normal for scanning?
Are you seeing this with multiple VP8000’s?