Neatly done open-manifold should not be a problem. Both are non-manifold but only the smoothed one has collision problems. To check though I made a smoothed closed-manifold version (attached) and tested that. Same issue.
I'm using blender and it's export script for DAE- and it does smoothgroups at the most base level - by splitting the 'smooth groups' off into separate groups of polygons. (It's actually more powerful than defining smoothgroups but must be applied before exporting which often gets forgotten!).
The issue here is either going to be: how this kind of DAE stores smoothed data as opposed to faceted data, and/or how PCS2 interprets that. I can't find any pattern to what specific smoothed geometry generates the error.
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