What's needed to get Views data export working with a Block view?
I'm one of the maintainers of the module - I run the firm that built it https://www.computerminds.co.uk/articles/views-data-exports

I've just done a quick test locally and I can't seem to replicate the issue, I have a view with a single block display to which I add a data export.  I assign a path to the data export display and attach it to the block display - and it all seems to be working fine.

Could I ask which version of the Views Data Export module you are using?