We have a full backup of the job folder when the issue was occurring this time. I attached the polling log from one of the branches in a multi-branch pipeline that was having issues.
It seems to be checking the included libraries and finally the specific branch but the log never shows any changelists that it identified as being new but yet still says "Changes found" at the end. The only thing that my untrained eye sees that might be concerning is "no polling baseline in <path>".
I can provide more details if needed.
bradleywehmeier adding Brad to the thread for more details.