OK, so despite earlier posts to the contrary, I'm not the only one having this issue.
3DXchange 7.21 definitely has some kind of problem with Genesis 3 characters and this is complicated by the fact that not all Daz Gen3's will fail to import.
RL, my concern is, once we figure out WHAT is causing this and file the issue in the tracker (and this becomes increasingly less likely as more of us revert back to 3DXchange 7.0 and 7.1), will we have to wait months AGAIN for a fix? Gen 3 import wasn't working properly in 7.2, now in my case, it's worse in 7.21. My project has over 15 characters and yeah, they're ALL Genesis 3.
My hope is just that there isn't silence on this issue for the next few months.
Anyway, back to the problem itself. I have updated the Daz facekey to the 7.21 version and added the morphs to the correct locations so I don't believe that is the problem. Also, after reverting to 3dX 7.0, it seems to have no problems recognizing the characters with the 7.21 morphs and facekey. I'm also importing animation in the 3DX import settings, so that shouldn't be the issue.
The big problem for me is that the auto recognition of the Daz Gen 3 skeleton (or whatever it is that 3dx looks for) doesn't kick in at the beginning. If I manually assign a profile in the characters setup, the model is successfully made into a non standard character. The problem is this doesn't also run the automatic assignment of face morphs. Maybe that's what gave rise to
This feedback tracker entry.
However, if I understand the problem properly, the deeper issue is that 3DXchange just isn't automatically recognizing the model on import and therefor skipping the essential auto assignation of the face morphs. If we knew what new thing it is we need to do to these 'bad' Gen 3 models, presumably we could get this to work, provided this new step doesn't take too long per model.