Are you sure you have items in your inventory for it? There's a message at the bottom of the description if it works (just in case someone didn't see it, says Gale can consume it on its own line). I've seen it where it shows what everyone is carrying that he can consume in like separate selection / inventory areas by people where it just shows the consumable items. I've only done it a few times though so could be a bug. I don't think it'll show if it's in your camp inventory either, current party only is my guess. I made a warlock so I don't usually have him around much and only have done it at camp.