Using castle magic to disable mounts works great. However, if you enter your house from a place that doesn't allow mounts (such as a dungeon) the castle magic will actually force you to have your mount equipped rather than force you to unequip it. If you try to unequip your mount during this glitch it says "you cannot equip a mount in this area!" which proves the castle magic is still working.
I can understand why this glitches but if you could fix it that would be much appreciated.