Remember that I edited that domain on the site to test it? The site broke. I put it back, but it was still broken. I cleared the cache -- still broken. Then I shut down my browser and restarted -- and all was well. So weird. I do think that a ton of the issues we have around domain mapping are cache related. There are caches in the browser, the server, and who knows how many stops in between.
When I look under network admin-> sites, I definitely see both mapping definitions.
Maybe delete the one that isn't showing and re-enter it?