Thickening a surface seems to be somewhat spotty as to how well it works for me, hopefully this post will clarify a few things.

The attached model is a surface that has been thickened. What cost me hours was that it wouldn't thicken unless I did a surface trim, making the surface arbitrarily smaller. After the trim, the thicken works fine, but if i suppress the trim, the surface wont thicken.

Using the check tool, I don't get any alerts with or without the surface trim.

I would love to resolve what is going on here, because the thicken tool could really save me some time on a lot of projects if it would work more predictably.

Thanks for any input.