When using Reminders, if you 'Manual Retry' you receive a message for a reminder with valid criteria which won't run stating "Reminder Manual Retry completed. Please use the View Last Run action to view details regarding messages generated for this reminder"

However, there are no messages generated in the event where a reminder has been run on a particular record. In order to have this run successfully, you must check "Retry previous successes" when performing the manual retry - though this is not indicated to the user. Throwing a message which indicates this would allow the module to be much more usable for individuals who get frustrated thinking they have done something wrong.