The HP1 is quirky on how it chooses sites when you hold. I will need to double check, but if I recall correctly, it will hold on a single site when you hold on a system or channel. The problem is that it may hold on the incorrect site that does not carry the talkgroups you are looking for. Also, when holding on a System or Channel for prolonged periods it will also sometimes change to a different site if there is a dropout in signal.
Try holding on a department, and I believe it will continue to monitor all sites that are not avoided.
Interesting you mention that. My scanner was exhibiting that exact behavior and I thought I was going crazy. I will try that out. Thanks!
Also, when was the last time you updated the DB in the Sentinal software and wrote it to the scanner? Mesa's TRWC changed frequencies a few months back. If it has been more then a year, then Chandler's RWC Simulcast C changed frequencies since then.
It was only two or three nights ago. I verified the update both in Sentinel and on the device as well (turns out I do have the extreme update).