Maya to substance UV borders get messed up

Hello everyone,

I've been wrestling with a problem for hours, trawling through youtube etc and can't find what's causing my problem here.

I have a model(s) I've built and UVd in Maya as low poly with the idea I subdivide it later for rendering.

The issues being when I subdivide the mesh and take it into Substance. Following Substance training videos I use "convert smooth preview to polygons", load into Substance and all appears good.

It's when I bake my mesh maps (4096) that I get the first indication that all's not well. If I view the mesh maps I'm getting horrible stretching and seams at the edges of my UV shells. I don't see anyone else having this problem?

My UVs in Maya are not overlapping.

I'm pretty green to Substance so if someone could point out what's going on that would be fantastic.