I am running an MultiSite network on live and staging. In live, everything seems to work fine. In staging, recently something must have changed and now my staging sub sites are not available. I don't know what happened, but I may have network deactivated domain mapping and it seems the mappings may have been lost. Not sure. Is there any way to trigger mapping again for sites in the network?
I can give you access to the admin to review.
Here's a link to a subsite in staging that was live a few weeks ago, but now does not resolve.
But, the first site in the network, jazzboo.staging.wpengine.com resolves correctly.