Light/shadows not updating after modifying meshes

When modifying meshes at runtime, some shadowing artifacts appear.
We have marked the meshes as dynamic, but we think there might be some raytracing related acceleration structure or similar that is not being updated after modifying the mesh.

See below for a before and after, the darker rectangle in the front face of the second image looks like a remnant of the original shape of the geometry (it shouldn't be there).

Edit: The problem is not observed if a new mesh instance is created after every change of geometry, rather than reusing the same one.
Also, calling mesh.MarkModified() doesn't seem to have any effect.

 

We had the default 'dynamic transform', I will change and test.

 

That was it, great, thank you!