How do I include a unix filepath in my metadata

Please forgive me if this question has been answered, I am trying to use beamer and scrivener together and I would like to specify a file to be used as a titlegraphic in my metadata file.
When I insert the line

Titlegraphic: /Users/amd/Dropbox/8-Admin/LiverpoolLogos/colour_logo_0616.png

All the slashes are converted to ‘\slash’ sequences. How do I get it to insert the filename literally? I have tried enclosing it in but that doesn’t help.

Thanks

Andrew

Would it not be easier to include the PNG file in your compile output location, and reference it relatively?