No push-notifications for mails in subfolders (Notifications + Badge Counter)

I am having the following problem:

On my Exchange mailbox, I've set some server-side rules to automatically move certain mails to subfolders when they arrive (for example, all mails from *.apple.com are moved to the folder "Inbox > Apple"). The Mails are also being successfully moved into their designated folders on my sever and also when I log into my Apple Mail Apps (Mac, iPhone).

However I don't get a push notification for Mails arriving to the subfolders, whereas I got notifications for Mails on the normal Inbox! This is happening since several years.

I am using the german Mail service www.gmx.de and my account is set up with imap.

In my settings (under the "Mail, Contacts, Calendar" settings, Exchange mailbox, Items to push) I already selected all subfolders.

I also read that other users have had the same problems. Does anyone has a fix for this? Thank you!