Does that happen only when switching snapshots, or also if you directly load that snapshot after starting Ardour?
“LTC in” is a reserved port-name (always present), perhaps it was accidentally saved in the older snapshot, I dimly recall a bug related to that, but that was a while ago, and only present in some git revisions.
Would you mind opening a bug report at tracker.ardour.org and attach the .ardour snapshot file that exhibits the issue?