I caught an Eevee from Route 116 (Hoenn) which innately learns the move Covet. According to bulbapedia, this move should steal an item (if its successful) permanently from wild pokemons and trainers as far as Generation III.
I used this move twice to two different trainers, the Rich Boy and Lady in Route 116 (that need HM Cut to be accessible), and the on-battle screen showed "Eevee stole the item Nugget" from both of the trainers' Zigzagoons. Afterwards, while still on the battle, I can see my Eevee having the hold item icon (the green, cylindrical one) on my party bar. But when I check Summary, it says "No held item" on my Eevee. I checked again after battle, and the hold item icon is now gone and there's still no hold item in my Eevee. I checked my bag and there's no Nugget to be found.
Is this supposed to be intentional to avoid OP money farming strat or something like that? Or it just happens to me?
Thank you!