Problems with mesh collider

I'm working on a minigolf game. The course is made up of many modular pieces, and all of them have their own mesh colliders, generated by unity on import. They are placed at the exact same height.
Now when I hit the ball and it gets to where their edges meet (which are at the same spot), it behaves like it hit something and either bounces back or "jumps" a bit, like it's a ramp. And it happens with physics solver iteration count: 8 and continuous collision detection on the ball.
I also tried discrete collision detection first, in that case, in addition to the bumping into edges, if it hits a surface with "high speed" that is not parallel to the direction the ball is going - like a ramp with an angle of roughly 25-30° - the ball just goes through the mesh collider.

Any suggestion how I should set it up?
Thank you in advance