Skeletal Mesh Actor to Static Mesh and export it to FBX Problem

When I convert Skeletal Mesh Actor to Static Mesh and export it to FBX and import it back to Unreal, one material slot disappears.
If I import this FBX to Blender, one material slot is missing, but there is no problem if I import it to 3D Max.

How can I maintain the Material Slot?

Unreal engine 4.27 and all import, export settings are default.