Hello not that far from you!
The PRI button is used JUST FOR analog frequencies. For Clare county the fire dispatch still using 155.265 so I assume thats what you have as priority. If Clare pages out over the MPSCS as well as 155.265 and I suspect they do, you could turn off PRI and eliminate the skipping.
To put talkgroups on priority you need to put the priority setting to on for the system(county or city that is) and in turn turn on priority for the talkgroups you want. Understand you CANT just arbitrarily turn on priority for any talkgroups like with analog. The talkgroups in order to work as priority MUST also be set for priority officially by the radio system 911 itself. Normally fire, police dispatches work on priority, sometimes others will too.
Way I found the otter talkgroups using priority officially was turned on priority for talkgroups I suspected were. Then when I knew they were being used I manually would HOLD on a different talkgroup and if the scanner switched to the other talkgroup I set for priority, then I knew that is set for priority officially.