Hi Jurgen, yeah I think those thin tips that come to an exactly flat spot from opposite sides are causing the problem.

I did a quick experiment where I hacked those tips with a plane and then that allowed me to put a small fillet on things.

But you probably don't want cuts at the tips there so you may need to make those tips come to something more like a 20 degree angle at their ends rather than coming to a 100% sharp flat tip.

- Michael