In Unitrunker, "XP" = patched talkgroup. If you open the system window of the system you're monitoring and go to the "Patches" tab, you can see which TG's are currently patched. I'm not sure what you mean by "won't follow it".
XP is a cross-patch. Two or more talkgroups are temporarily fused into one. Double-click on the group ID to see which other groups are tied together. These show up as "Adds" events in the history panel.