The issue here seems to be because the schema is attached to your entry-content element and you’re adding the title/sub-title to the content, so it’s being parsed as part of your content.
Not sure why they’re not adding spaces – that part is definitely strange.
My suggestion would be to disable the structured data as it is now:
I’ll dig into it a bit to see if it’s something we can control. I have a feeling this sort of thing would happen with a regular H1 inside your content as well.
I think JSON-LD is the future vs the HTML markup, anyways. Definitely worth exploring π