Moving an estimated tax payment early

I have my estimated tax payments entered as scheduled transactions. I'm going to be making what would normally be my January payment on December 15. I edited the transaction in the Bills & Income window to reflect a December payment; however, when I look at the register for my checking account with reminders for the payments due in the next 30 days, it doesn't show it as an upcoming payment. If I change it to show reminders for the next 60 days, it shows up as a scheduled payment on December 15. What's up with that???