The 4th doctor's scarf will barely show up on me at all, just as a dark shape, even on an armour stand.

This sounds as if it is a problem with your graphics drivers?

Do you know your graphics card?

This is usually a pretty common bug on older macs

Sorry, I don't really know what a graphics card is and yes I do have a quite old MacBook air, with a broken screen.

Probably a clipping issue with the model mixed with the black render issue from macs

So how do i fix it?

All I can suggest is trying to update the graphics (I assume they are old Intel HD graphics kexts)

Or using a different PC, this doesn't sound like something we can really fix.

 We can always just make a better model that doesn't clip

It's his computer not the model.

Changing the model to a not-flat one will fix the clipping issue

OK, thanks for all the help!