As an alternative to hex teleporting, you could make a new save and copy the world.x0 file to another location (such as a subfolder). After loading the save, you should be able to take the stairs up, get the cutscene with Arhu, and then save again. In this latest save, you can then replace the world.x0 file with the one you moved to a different location earlier. As long as the problem is limited to just those stairs, putting the original file back after you are past them will avoid the stair problem without the side effects of reverting to the default world file. Keep you original save, though, until you determine if there are any other problems with Iona's dungeon.
