Thanks @h_classen & @Daniel.
For anyone still confused by this, the process of exporting an SVG from Hype that works for me is:
Open the Hype document in Hype 4
Select the vector shape and cmd-c copy
Paste the text that is copied into a text editor
<SVG...>...</SVG> text (excluding the
Open a vector editor (I use Affinity Designer)
Create New from Clipboard
Export as whatever.svg (or any other image format you fancy)
It could be that I'm overcomplicating things (if so all suggestions would be welcome) but the above does seem to work.
@Daniel it would be lovely if a future version of Hype had an export SVG function to streamline this, or even just a 'copy SVG to clipboard'. Hype's pretty excellent for SVG creation - I actually prefer it to Affinity Designer for creating bezier shapes and paths. It would be great to be able to generate icons, etc. from Hype without needing the above 7 step process.