Mesh with more than 65535 submeshes is not rendered correctly

We want o draw big models with big number of vertices and indices using a single mesh.
It seems the mesh is not rendered correctly if we have in one mesh more than 65535 submeshes, although we specified the index format of the mesh to IndexFormat.UInt32.

I don’t really have an answer for this. This may be an internal hard limit of the Mesh class. However why do you have 65k+ submeshes? You only need a submesh if it either has a different topology or a different material. Why do you have that many? What’s the point of creating a single mesh if you have that many seperate things? Submeshes do have overhead as well. From your screenshot it’s hard to tell what that thing you’ve loaded in actually represents.