This is a question that is probably better asked to the Moho programmers, since Moho 13.5 was fairly recently released. Since Moho supports direct import of Poser format, the support for Poser 12 import may need to be updated in Moho for Poser 12, and not vice-versa.

Thankfully, Moho is now back in the hands of the original programmers instead of Smith Micro, and I believe they still have their support forum on LostMarble. You can find out more here:

https://moho.lostmarble.com/