Create options missing from Material Request

Howdy! I’m in the process of customising ERPNext for myself and have hit a bit of a weird issue I cannot work out…

I can create a Material Request from a Sales Order (great) but after submitting the Material Request I get no options for creating a Purchase Order or doing anything else. Simply a blank dropdown? Likewise, when I try to create a Purchase Order from a Material Request there is nothing listed.

This topic mentioned info in products could be the cause but no explanation of exactly what info might be missing? Any help greatly appreciated!

Thanks,
Dan