Our sister company has been experiencing an issue with EPDM.  The "send email" action seems to be acting up and is not always sending an email during a state transition.  Sometimes it works and sometimes it doesn't.  Have you seen the same thing with any of your workflows in 2013?

It is random, a transition will work one time... and then the next time it won't.

They are running EPDM 2013 SP3.

Gary.