Thanks for your suggestion John, I did try this and it did work, so apologies. I realised it had to be something to do with our build script. We have it working now so many thanks for everyone with their help.
> description: |
> Some long, perhaps multi-line description.
>
> Sadly this *does not* appear in the epub (2) metadata when we build it, it
> used to work. This does seem like some sort of bug? Because if we use
> commas to surround the description text or use '>-' as suggested by
> Albert, the description *does* appear in the epub metadata. However, we
> have a lot of markdown which use the '|' formatting for multi-line so I'd
> rather not have to change this is I don't have to.
It works fine when I try it...
If you want us to look into it, upload a minimal markdown
source and exact command (and pandoc version) you used,
together with the resulting epub.