There is a setting in Preferences that you should check.
The setting is on the 'Network' tab. 'Auto-commit Reminders (applies to current file on this computer)'
It is my understanding that this setting will only appear if you are syncing your data with other computers. It is also my understanding that it is best to only apply this setting to the Primary data set. Applying it to Secondary data sets may create duplicate entries in certain circumstances. Again, this is my understanding of its workings.
Reminders only auto-create when you launch MD.
Have you checked the auto commit box and also that the destination account is correct?
Can you send a screenshot of one of the reminders in the edit screen?
Can you post help/console here?