Handles in the halls of Fnuk can't be switched when you have an elemental shard equipped.
I vaguely remember this bug has been reported before but couldn't find it, so my apologies if this is a duplicate.
When you have an elemental shard equipped, it's impossible to switch the levers in the bottom level of the halls of Fnuk. When you stand on top of the lever and press 'u', you see a list of items you may interact with, and the lever doesn't appear in that list. Apparently the shard replaces its entry?