Q: ServerAlias broken?

Admittedly, I've been slow in moving services over to OS X Server El Capitan. Life was crazy the past year. I just started moving sites to 10.11 last night and noticed that ServerAlias ("Additional Domains") doesn't seem to be working properly. When I add "domain.com" for the Domain Name value, and then "www.domain.com" to the Additional Domains, I'm forwarded to the wiki when I attempt "www.domain.com". If I create a second website entry specifically for "www.domain.com", it works. That implies my DNS, etc. is working correctly and that something is broken with ServerAlias. I'm looking back and forth between my Mavericks and El Capitan server setups, but am unable to see any difference in configuration. I'm about to dig into the Apache configs, but if someone has seen this and knows what it is, that would help.

many thanks,

Jaime