I've hit the same bug on occasion, it's very strange - the same site will do this locally, but then not when installed on a live server. I wasn't able to track it down, it seems like an environment related issue.

Pretty sure I reported it on github at one point but I can't seem to find it.

I think that you'll find that if you add a layout, then refresh the page, the layout will appear and you can use it without issue. It's a nuisance (and not client friendly), but it doesn't stop you using layouts. Again, this doesn't happen everywhere, the bug just pops up on some servers and not on others.