Some items will super glue them selves to the floor where you first dropped them, no matter what you do. All but one circlet cannot be moved, a few helmets and other assorted items. One of my characters is having trouble moving dwarven helmets and all the others can, so no idea why it would change.
Even if the physics is normal for the item (Sjyrim normal) if you add it back into your inventory you have to drop it and rush out the door all over again.
On the PS3 items you move can return back to where they were dropped, sometimes after the room as been loaded a fair few times and everything was OK. If you are on the PS3, you will just have to keep trying, maybe try saving the game after it is dropped and then loading that save game and then rushing out the door. Also on the consoles to prevent memory issues, do not drop too many things, do small batches like 10 at a time.
Items sitting on top of the case might mean you are trying to put to much in there in one go, the item is glitched, or the display case just plain does not like it.
I know. It's pretty bad, huh?
Worked fine in Morrowind and Oblivion...
That's progress for you.
Actually I have no idea why they just made the display cases empty boxes...
Why you don't 'click' to place the weapon (like ie. Hjerim).
I have a mod that fixes the manor on Solstheim...
Surely there is a good one for the Hearthfire homes?
(my new project - I'll let ya know)
Display cases are useless. Just sell everything and you will not need them, so less materials toy use up on stupid junk.