Out of sheer curiosity, why does Intuit ask its admins post the boilerplate suggestion to clear browser caches or use private windows (implying the issue is with users' browsers rather than server-side code) when not a single person who has reported this issue in this thread or any other has found that suggestion to have any impact on the matter at hand? You're intentionally misleading/gaslighting your users at this point by telling them the problem is something they're responsible for, which is disrespectful and counterproductive in terms of working toward an actual solution.

Your code handling reminders is broken, and it has been for quite some time, as seen by the history of reports on this subject. Why not just acknowledge that fact and ask users for help in troubleshooting specific scenarios if you're having trouble replicating them? I'm sure I and many others from this thread would be happy to contribute time toward testing fixes if it finally resulted in a resolution to this longstanding bug.