Skeletal Mesh's material list is flickering in Details window

At first, import some FBX file and drag it to Level.
When click instanced mesh, Details window works with material lists.

And go straight to Project Settings > Rendering and change some options like Nanite that restarts the editor.
I can find compiling the shaders at splash screen and also loading material popup at right-bottom side of opened editor.
Last I click some Skeletal Mesh in Level, somehow Details window starts show and hide all material lists and editor freeze almost infinite times.

I don’t have any clue except industrial mesh(with bunch of materials) with 5.4 version.
Is there recommended material counts per mesh usage?
Why it happens and how can I fix it?