Reminders not appearing in Notification Center today view

I am having this exact same issue. Sometimes a reminder due today may show for a few seconds, then disappear.

Me three. I tried renewing the UUID like some have suggested but still no joy. Not sure if it's related but also having trouble with Favorites/Tags/etc showing in open/save dialogs.

Same here. Any news on how to fix it?

Not yet. Don't know if it's a widespread problem or not. Maybe is but people haven't noticed yet. Depends on how many people use the Reminders widget. I've also noticed a couple other problems that may or may not be related: Items in the Finder window sidebar missing for open/save dialogs, and opening things using "Open Recent" in apps like Numbers. Sometimes there's nothing in the list and sometimes when I try to open an item from the list I get an error saying "Can't open because the file doesn't exist". But I can still open it using the regular Open menu. These things may not be related but they seem like they have a common theme: aliases or pointers to other files not acting correctly. I don't know enough about how these things work in the background so don't know if it's all one big issue or several smaller ones. Either way I do have confidence that Apple works very hard to fix things like this. My only concern is that there are only a handful of people that notice the same thing and maybe it doesn't get addressed. We'll see. I'll bet there will be an update coming fairly soon.

I am seeing this as well. I did a fresh install of OS X El Capitan to kill some issues I was having with Hand-off. I sometimes see the reminders appear when I slide out Notification Center and then they disappear.

Mine don't appear at all, but it almost looks like the window is resizing to accommodate the reminder list.

It seems I got a workaround. Just move the scheduled reminders to a new list. Then delete the original list. You can now see the reminders on the notification center. You may see some cut-off reminders on the top of the notification center screen. But after deleting them the rest are shown correctly.

It has been working for a couple of hours. Hopefully it will stay that way.

I hope this workaround will solve your issue too.

Might have something here. Deleted all Reminders lists, then recreated them. Added some test reminders and they all showed in Notification Center widget. Was also able to delete them from the widget. Looking good so far.

note: This was after the El Cap update to 10.11.1 but the widget wasn't working right afterwards. Only after following the outlined steps here did it start working again. Still going to hold out for a day or so before checking the "solved my issue" box.

Great. Good to know

I didn't move them all to new lists, I just deleted all the old 'Completed' reminders and that worked for me.

I'm declaring this SOLVED for me! I went the route of moving all reminders to different lists first, then deleting the old lists and renaming the new ones accordingly. It sounds to me like just deleting the completed items may have done the same thing, as I think both procedures have that in common. I would probably suggest trying the easiest way first (just delete the completed reminders) and if that doesn't work then do the move & delete process. Either way I'm happy to have them working again. It's amazing how dependent I became on having that checklist always available in the Notifications Center.

Theory:

I'm wondering if a lot of the issues I've seen might be related to certain support files being duplicated, locked, or otherwise not accessible to the associated app after the El Capitan upgrade. I'm still having troubles with Open/Save dialogs missing sidebar items. Also the Recent Items menu in the Finder and some Open Recent menus are not working. Just feels like the system is having trouble locating preferences and settings or something. For what it's worth...

New theory:

Even though I think I've fixed this bug, I have been experiencing other frustrating issues:

For me I think a lot of my issues I've been having with Finder window sidebar items missing, open/save dialogs missing sidebar items, Recent Items missing, Open Recent missing, etc, etc, etc, have all been due to some corrupted files that got copied over when I used Migration Assistant after the El Capitan upgrade. The reason I feel this is the cause is that the other day I tried to open a label creation/printing app and it wouldn't open. It had been opening slow for a while but this time it just hung. So I created a test account on my system and when I tried to open the app there it opened just fine. Also I could use all of the broken things mentioned above without issue. Granted I was only in that account for a short while but it sure looks like my troubles are contained in my user account and not system wide. So I'm going to wipe the drive and restore files and folders manually. I'm not going to let Migration Assistant copy over all of the preferences and settings and everything. It will take some time not only to rebuild everything but to go through and set it all up like I like it. But for me I think it is the only way to clear up some (hopefully all) of these issues. Just wanted to throw that out there.

This "worked" for me as well. Here's what I did.

1. Create NEW LIST NAMES for your reminders
2. Move OLD LISTS to NEW LIST
3. DELETE old list (this will automatically delete the "completed items")
4. Notification Center WORKS!

I've found this article that could instruct you on how to solve your problem:

http://apps-reviewed.blogspot.ae/2016/12/how-to-fix-reminders-not-updating-in.ht ml