The only time I've seen this happen, it was caused by an objct placed
too close to the bed. Some objects have invisible, extended front or
back ends,(for example, a door, whose area extends one space away
from the wall on either side), can cause this to happen while not
appearing to be in the way. Try moving objects near the bed around.
If this is not caused by an object in the way, then it's a bug I've
never seen before. Hope this helps.