I recently merged a package of fixes for the advanced inventory manager. One of 'em claimed to fix the directionals; mine acted up during testing and I wrote that off to their being wacky and the fix being overridden by my local settings. Rebound mine and all was well.
I was wrong: the “fix” appears to have erroneously rebound others’ settings as well. I’ll see about getting a correct fix up. If you’re using 2138, you may have to manually go in and unfix the “fix”. Hit ? in the advanced inventory manager to get to the keybindings screen for it, and rebind yours appropriately.
My apologies, all.