My question was does YOUR circuit have an inverting driver like a MAX232, not the commercial product which typically does. Please post a link to the converter you bought - then we can look and tell you if it requires inversion or not. (Or you could do it yourself) The "invert / don't invert" thing is left over from a time when it was much easier to build an inverting output stage than a non-inverting one, and in order to work reliably you needed higher RS232 voltages than today. Unfortunately this has led to lots of confusion as something that "everybody knows" is no longer common knowledge, and not even taught to newbies.

The PIC by default expects to have an inverting driver in it's circuit, so it sends stuff upside down, knowing it will be put right side up by the rest of the circuit before it goes off into the real world.
SOME PICS (NOT all) can be told there is no external inverter.

Related topic, setting TRIS for both will completely break the link. It has nothing to do with inverting data.