Reply To: The mesh for the Skin mesh modifier on the arms is not appearing.

Any chance you have any add-ons enabled?

Box cutter or similar?

These add-ons can disable ‘display in edit mode’ on some modifiers even though its still visibly active in the modifier panel.

Try turning it off and on, if this doesn’t work, disable any add-on in the preferences, 

if you have no add-on active, I’m stumped 🤔