The reason is that Poser and Studio do superconforming in different ways, Poser's is a bug that they havn't completely stamped out so it can be forced, studio's is intentional but there are ways that it can be screwed up (Such as the conformer not having the channel that the erc link is pointing to), but that doesn't mean you can't get it to work in both, Unfortunately its really impossible to guess why its working in one and not in the other without looking at the cr2 itself.