I've come to find that recent newly added devices seem to generate alerts and events correctly in DFM but no emails are sent.
DFM 2.0.12, was on 2.0.11 but the same behavior is still occurring.
These devices are the same models already managed and do show up in groups, etc. They are 3750 and 6509 series switches.
I am still receiving alerts from any existing devices as configured, its just these new devices that I've added in the past 4-5 weeks.