Ok so as far as I know this bug occurs only when AlchemistNPC mod is installed, AlchemistNPC Lite works just fine, so for some reason, AlchemistNPC breaks AutoReforge I don't know if it's my fault or AlechmistNPC creator. I will try to fix it but for now, you will have to uninstall either AutoReforge nor AlchemistNPC
It's failing for me using AlchemistNPC Lite as well. Most recently, and consistently, I had an issue with both the stardust cell staff and stardust dragon staff. Both of them failed to enter the reforging window. I believe it's an issue with the "Charm of Luck" included in AlchemistNPC Lite. When I took this item out of my inventory, the reforging menu was working as intended. Look into that being the issue.