Same issue...
Noticed a possible bug after doing the latest HP-1 firmware update:
When holding on a system (top most display line), HP won't stop on any active talkgroup while in hold mode. After removing the hold (yellow off), it works normally.
Also, the previously mentioned bug that the User ID mode 2 returns to "OFF" after power is cycled.
Mine actually did this last night. Was holding and listening, on a system, (Mot Type II, analog) for about 4 hrs or so....some time along the way it got quiet. Thinking it was just a slow night, I didn't think much of it, until I was swapping out the batteries on my 396XT, and turned it on to check the fresh batteries. While doing this, I was hearing traffic on the same system through my 396XT, but the HP-1 was silent. I actually stared in disbelief for a second, looking back and forth between radios....I'm sure it looked comical.
I tapped the top line at this point...releasing the hold and as it scanned through my list and hit the system (as it returned in the scan) then it started working fine.
I will point out too, that I heard the morse code identifier beeping for the radio system sometime during the quiet phase...I thought that was odd but shrugged it off.
In my limited knowledge on how this thing operates...it almost sounds as if it missed the control channel moving to the other frequency. This particular system control channel changes in the evenings routinely.
I have posted this possible bug to the Uniden website also.