Hello @BCassill
Thank you for reaching out to the Community regarding your issue, although I am sorry to hear that you are experiencing issues with reminder to sync not working properly. I'm wondering here what might of caused it to stop working since the recent update. To start off here first thing we can attempt is to reset the alerts so this way we should ideally see it pop up again. To do so you'll want to go across the top to edit > preferences > Alerts and Messages > reset Quicken Warnings.
Once you get a chance to try to reset the warnings let us know if you're able to get it to pop up again. If not we'll see what we can attempt next to resolve the issue.
Thanks,
Quicken Francisco