Okay, another conundrum.

I can book the flights with cash Roundtrip, as in it allows me to get all the way to payment. But I am trying to book each leg separate.
AND I can book my return flight to the States one way without issue (I do not wish to do that yet)
BUT I can't book the one way flight down to SXM no matter how many times I try.

This makes no sense. I know the usual is you get a message on most airlines that says you have to provide proof of a return ticket warning but I am not even getting that (and "technically" I still have a one way return ticket to the States with JetBlue though I get the feeling that too is not long for this world).

I know pulling my hair out will not benefit the situation but this has me mystified.