The Poser core figures from Poser 9 onwards have a different rigging system than Poser core figures of Poser 7 and earlier. Carrara has no problem with Poser 7 figures like Simon and Sydney, but does have bending and posing problems with Tyler and Miki 4.

I really don't see a path to updating Carrara to correctly interpret newer Poser rigging. Of course, the older rigged figures still work fine.