I put in a ticket and UD confirmed it was a bug. They asked me to make an adjustment in a file to debug, but I haven't done it yet. I will try and get back to them today. But there is an easy workaround (IP address) so I imagine they will just wait to the next point release to address it.
My point in this post is, even if they fix mDNS in the Polisy/eisy, will UD Mobile no longer allow us to use hostnames in the connection, i.e., is the user interface (in conjunction with Apple Transport Security, evidently) limiting the value here to IP Address. I will note that the name of the field is, in fact, "IP Address." Don't know if it's always been that but in hindsight it's pretty clear that's what UD Mobile user interface wants in this field (albeit with an "http://" in front of it).