I'm not totally sure what the problem is here, could be one of two things i'm assuming. After the civil war in which I sided with the Stormcloaks, when the new Jarl and staff take over Morthal, at nighttime Arrald Frozen-Heart and Benor are stuck outside the guardhouse, trying to get in as is evident when they periodically do the open door animation, only the guard house is locked, keeping them outside.
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If I unlock the door, despite the small bounty, the 2 of them finally make their way inside and go to sleep, the bug I thought is that they just can't access the guardhouse properly. But after that I noticed the stormcloaks inside the guardhouse just stand about, there are four in total and four beds in the guardhouse making me wonder if Benor and Arrald are even supposed to be in here at all. To be honest I can't remember where Benor ever slept pre-war, he always stood outside the guardhouse.
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So the issue is one of the two, there is an unused bed in the Jarl's house that goes unused that Arrald could sleep in, though the room Arrald is in all day has a bed but I think Teeba-Ei tries to sleep in there, though that's another bug I reported. Hopefully in all this mess there is an answer.