Using Convex Decomposition Makes Player Fall Through Floor

My character is a railcar, and I am using physics to push it along the rail. The problem is that when I use basic collision options available in the mesh editor, the railcar hitches along the rails (not smooth) because of all the rail pieces that make up the tracks.

I tried using “smooth edge collision” on both the rail and the railcar. Both have a super slippery phys material attached.

I tried using the “Convex Decomposition” in the railcar mesh and it makes it run a lot smoother but it will randomly fall through the rails now.

The railcar I got is from Quixel assets.

Any suggestions would be helpful.