Hi Ticker..
I am not an immigration pro, but logic tells me that she should not apply for a finacee visa. As you said, she is still married. Fiancee visa is for those who can marry within a certain period of time. In your case, or her case, there's not even a guarantee that she can marry you within the time frame specified by the visa. This could be the reason why her visit visa has been refused as well.
Surely, someone here can give a more technical answer.
Welcome by the way!![]()