Skip ahead if you’re not having any issues with the Mail app:
My iCloud Mailbox in the Mail App hasn’t updated since last night on my iPad, and now I’m seeing this morning that my iCloud mailbox in the Mail app on my iPhone isn’t updating, either. And I’ve found this causes issues with the All Inboxes folder, too. The Mail App on my Mac is fine, and reflects what the web is showing. If I go to any of my other mailboxes on my iPad or my iPhone, any of those accounts folders I go to update immediately. I’ve even tried moving a few emails around in one of my Gmail accounts and in my outlook.com Email, and any changes are reflected right away on both my iPad and my iPhone. The app is working, just not working well with my iCloud account. I’ve reported this SO many times to Apple directly, and have mentioned it ad nauseum here in the forums, too. The only thing that keeps me posting about the Mail app is that there are still some, albeit few, folks who also have problems.. I’m trying to think what kind of commonalities there could be considering most people, it seems anyway, don‘t have the same problems. But then it’s hard to know if they’ve moved away from that app. Considering all that’s happened with Edison’s app and all the talk about not using 3rd party apps.. Whelp..
tl;dr The Mail app’s worked fine and then hardly worked at all depending on which of the fourteen iOS13 updates (not counting beta releases) I’ve been using. And when troubleshooting iCloud mail issues on an iDevice, it seems that the only “Mail” options are to toggle it off & on again. That seemed to work for about an hour Yesterday. I really don’t wanna have to use the Gmail app, but at least I’ve got dark mode there now.
I can’t believe, even with how horrible iOS13 has been, that there can be THIS MANY issues between releases with a core app like Mail. It feels like there’s just monkeys banging away at a typewriter or something. If only they could push out updates in the App Store for core apps like Mail.