Yes, topdog is right.
The dovecot.org list told me dovecot ignores alias mapping. Since the postmap command showed the alias address was properly output, I looked at where in between postfix and dovecot the alias mapping was being lost. I did some research and I found that when using amavis, alias mapping was applied after it returned the message to postfix.
So I focused my attention on the master.cf in the amavis section. That's when I found a stray # found it's way into the line that starts with -o receive_override_options=
Stupid mistakes can be the hardest to figure out!