Changing the complexity of the desired mesh using the Hull Count, Hull precision and Max Hull Verts on Linux requires the process more time to complete, but causes no results. This process works as expected in 4.18 on Linux.
Results: The message Progress[100.0][Simplify convex-hulls:100][Simplify convex-hulls:100] appears, stays there, but no collision mesh is created.
Expected: The operation creates a collision mesh.
Note: Saving while the Convex Collision is at Progress[100.0][Simplify convex-hulls:100][Simplify convex-hulls:100], causes the message to go away but it removes any Simple Collision that was added to the mesh.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-59506 in the post.