Materials of Nanite disappear in UE5 EA

In UE5 EA ,When large assets are turned into Nanite, there is a problem with the material, and it is not displayed or blackened,please somebody know how to fix this ,thank you.

here check my video:


I’m having the same issue. It occurs often for meshes with 3 or more material slots. Meshes with 3 slots are fine sometimes, but one with 4 slots or more always collapse in my environment.
Number of mat slots may not be directly related to the issue but just stating what I found.