I've recently migrated a large number of changes to a custom module from our test environment. Since the migration our production environment does not appear to be generating any reminder notices. Assignment emails are being sent out however anything that uses the reminder module is not being sent.
I have looked through the mail queue and they are not even being generated. In the test environment I migrated from I have confirmed that they are in fact being added to the mail queue however this is not the case in production.
My best guess as to where the problem exists is with permissions. I've seen issues with test to live where certain role permissions that were in place before migration fail to work even though they are checked in the privileges section of administration (you simply deny and reapply rights to fix). I'm not sure what privilege the "send Reminder" notices would use and looked around but didn't find anything in the console.
We are running Service Desk 2016.4.