I think there may be a bug in tree collision optimization. I have a mesh that, when optimized, is coming out with a hole in it. See this screenshot: https://www.dropbox.com/s/1q89qet6oo93rv7/Capture.PNG
When I turn off optimization in the NewtonTreeCollisionEndBuild call, it come out fine, without the hole.
Here are the serialized files for both the optimized and unoptimized case, if you're able to take a look at the issue:
https://www.dropbox.com/s/xdjk90oxky1iy ... 5.bin?dl=0
https://www.dropbox.com/s/lf2yx3mzcw4ox ... 2.bin?dl=0
NOTE - I'm running on an older version of Newton from September 2016.