Thanks! :) I wish that was my problem but it isn't. My Mankey isn't strong enough to KO even paras with Covet and still I get no items. :( I tried to make it clear there were no factors that SHOULD be preventing theft with Covet in my case (I know I won't get anything if they are KO'd), because in every instance where a Pokemon that should have an item (Geodude, Paras, Clefairy, ect.) gets hit by Covet and survives, I still fail to get one 100% of the time. Mankey does not have a held item, either. It could be a bug, or it could be bad luck on my part.
I don't know what the rate of held items are for those Pokemon spanning from Pallet Town through Mt. Moon, but virtually every pokemon that COULD have an item has had one when I caught it, but absolutely none of them have been successfully stolen from when the survive the hit (which is often, because I only bother when I'm fairly sure the Pokemon will survive it). Neither Mankey nor Jigglypuff have stolen anything (and they themselves do not have items). Just seems odd to have that success rate when catching (a one-time thing given my limited resources), but a 0% steal rate despite using Covet (with the pokemon surviving) like 50 some-odd times. So maybe they really are THAT rare (which kind of makes me not want to farm at all if it's gonna be like that) and I was just super lucky with the catching, or something's not working right. Or, again, I've been absurdly unlucky when stealing from Pokemon known and confirmed to have items.
I guess the only way to confirm on my end if something is bugged is to get a Pokemon with frisk, and if I get positives on held items but can't steal them then something's wrong with Covet or my account or something. That's why I asked if anyone has used Covet recently to any success: so that I could rule that one out.