Hmm, I think you might have BOTH problems here?

Yikes to that craziness in the last picture! That's usually a gpu issue; whether its just an incompatibility in drivers/software or something more sinister I couldn't guess [tho if it went away when you clicked over there, I'd lean toward software issue, maybe?]. Keep you eyes open for other oddities in other programs tho, if you start getting artifacting like that in multiple places/programs where it wasn't before [unless you made a system wide change, like upgrading your OS]. that would be a pretty sure sign your gpu is preparing to shuffle off. If weirdness persists, it probably wouldn't hurt if you're up to it, to re-seat the gpu, and check the power connections/etc to it, they can occasionally vibrate a little loose over time, which can give you some display issues.

It is the same faces each time. If you look at the characters left ear, you can see an "L" shape above it, made up of correctly oriented polygons, and in front of that, you've got a "mutton chop" of inverted faces, then there's a 6 polygon [3 pairs] making a bit of a "triangle" on the forehead.

Interesting sequence of renders. The first Cycles render, is that using the CPU or the GPU [if i remember correctly, cycles can use either]? I know Eevee is GPU only, so I'm not surprised to see it rendering a mess. If something isn't displaying right in the viewport, its more often than not going to be wonky in a GPU render as well.

It looks like all the problem areas, are in UV spaces that are NOT the torso/arms. Are the torso/arms a single UV map? It could be something in the export/import that isn't liking the way the UVs are handled. Since it seems to switch between OK on the torso, and wonky right where I'd guess the seams are. It could be something that is parsing the first island/map correctly for the torso, then getting twisted up after that. I don't know what Poser's preferences are, but it could be something like poser wants the vertices at the edge of the UV islands one way, but Blender is looking for the data differently, which could hose your point order.

Also, worth trying some lower res maps, could be you're running out of GPU Ram if you're using high-res textures, which MIGHT be a reason why you're getting all one map in the render when you fill in the faces.

You could try playing with more import/export options, seeing if something works out, but if it loads fine in 2.80 but you're fighting it this much in 2.81, I think it may be best to stick with 2.80 and hope for the best whenever 2.82 ... or 2.81a or whatever rolls down the pipe. And keep an eye out for other graphical artifacts in case your GPU is staring into the abyss.

Wish I could offer something more definitive, or at least, more helpful. :(

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