Are you guys using the latest owner's manual or are you using the one that came with the radio? I think the one that comes with the radio is much older than the following which is in a PDF format so you can search it on your computer to find things faster.
Here it is in case you do not have it:
BCD536HP < UnidenMan4 < TWiki
When you see ID Searching it is in a trunked system and as one of you said it will stop on any TGID it finds but ID Scan will only scan the ones you want, but first you have to put those in.
When many scanners just say "scanning" the are usually scanning conventional channels which are not trunked.
Make sure you watch some of the video on how to do certain things it is usually better than just reading about it.
When I first got my HP-1 a few years ago I went into Sentinel and started off by making a favorite (did not put anything in it) then I went to the Main Data Base and right clicked on part of it and it gave me a menu and one choice was "append to Favorites" I did that.
Now I had way more than I needed in my Favorite's List but I could (while in Sentinel) click on the yellow star with a pencil to get me into Edit mode and remove all the stuff (in my very big Favorites list) that I did not want.
I also looked at how my computer had been programmed by looking at Sentinel after I appended all this stuff. I then could copy the method used, read the manual, watch some videos, ask question in RR and soon I was making my own favorites.