It seems like an old problem mentioned before, but it has gotten very serious since the last month or so, some time after Blackwood (not Blackwood itself) - I can confirm that because I did the same ignoring mobs and run.
Two examples:
1. Poacher's Encampment in Wrothgar: I went there to hit the mobs, unable to continue, so cloaked and ran across the river. My companion was already dead and mobs can't cross river so no pursuit. But it's still red and my companion didn't come back. This only ended after like 1 minute later.
2. In one of delves (forgot the name), I went to a doorless room which was empty, went out and suddenly I was in combat but nobody was chasing me. Some 1-2 minutes later I went back to that room, found an unaware enemy busy doing her stuff there - I guess she was just spawned before I went out, but she didn't notice me, didn't even become hostile until I got very close. The combat situation only ended after I killed her.
I know there is a timer of some sort, but what's the point of keeping combat mode when no enemy is even trying to engage players??