Of course. That’s what I have. It was some kind of copy/paste artefact in my post. I fixed it.
Yes, that’s the point. A YAML field requires only one colon. And dataview supposedly recognizes these as fields that can be queried. But if I use only one colon, the query returns nothing. It only works if I add a second colon.
If you need to use double colons, then most likely your frontmatter is not actually at the front of the file. Is there perhaps a line shift in front of the first triple-dash?
How do your frontmatter look like? Does it show the properties correctly when in reading mode ?