Not that this makes it better because I would expect that searching for an email address would bring back records created by that person, but another quick test showed that searching by a user’s Unique id does exactly that. So, you know, there’s that. 
I do wonder if this response from Emmanuel a few years ago (even though it’s in a different context) does shed some light on it, though…
In other words, email addresses are just, um, special, and you can’t do certain things on them that you might expect to be able to do.
Anyway, that’s enough out of me on this topic. If you do get a response from Bubble, I’d love to hear what the answer is.
Best…
Mike