Sorry to be short on my previous post. Only had a few minutes yesterday, and I thought better to send a hint, than to withhold a hint.
I don't know jack about Winlink! It seems a bit strange that PTT would be handled by CAT/ software for an optimized digital mode.
I know someone said CAT PTT is handled. (could be!) Well, did you sniff the com port and see if the CAT PTT command was actually sent?
Quick look at the CEC code and the generic ACK '0x0' word doesn't match the FT-XXX expected response..... I still would think that PTT CAT command would have had to gone out once to test for the reply.
Just thinking about the reported problem,