Undo function not working in ARAM

Not sure if it's due to unannounced undo-disabling by Rito or what, but the undo function doesn't work in quite a few of the games I play. I only play ARAMs so I'm not sure if it happens on SR or anywhere else. Once it happens in-game, it persists throughout the rest of that match. Very inconsistent bug and idk how to reproduce it but super annoying to purchase an item for stat check and then not be able to undo it since getting used to being able to undo things now.