The 'Model could not be read' issue is one of the TOOL's greatest mysteries, unfortunately.
Sometimes I have exported models in the same way as usual, but they ended up unreadable for no reason.
Can I ask what material you're using for the model? I've found that the Blinn material works best, generally being much less likely to go wrong in TOOL.
Sometimes I have exported models in the same way as usual, but they ended up unreadable for no reason.

Can I ask what material you're using for the model? I've found that the Blinn material works best, generally being much less likely to go wrong in TOOL.