Need Help with (UV's) Property Transfer

[entry-newspaper]

I need to unwrap the UV's on various client product CAD files. That process works much better (especially as I'm using FD Toolkit to help) if I perform that task with a relatively low-poly model. Great. I can do this.

However...

I need to use much higher poly models, for the actual rendering work.

So, I'm trying to use the Property Transfer tool to move the unwrapped UVW map, from the low-poly model, to the high-poly model. Things get messy from there. The UV's do seem to come across correctly, but I'm also stuck with weird artifact issues, around some of the model seams.

I'm attaching the most simply, stripped-down, example of two pieces. One is the low poly (source) and one is the high poly (target).

I hope someone can shed some light on this, for me.

https://spaces.hightail.com/receive/IPq6ilHP4Z