In-form stealing

Doesn't appear to work, everytime I try to steal I get the 'you couldn't find it' message on success. Happens with coins, items, anything. Perhaps because the monkey can't see into their inventory or something? I don't expect to give them peek but it would be handy :P I also tried 'steal 1. person' and get the same, even with a full inventory and loads of tries. Spider monkey.