[Shield 1] Why can I not "mark notifications as read"?

If you have noticed that you can't "mark as read" certain notifications in Shield, this has the following reason:

Notifications received in the previous month cannot be processed. Currently (and until further notice) this is due to system matters.

Please note:

If you do not want the "already read" notifications to be displayed in your view (data table), you can do the following:

Use the date setting - (top right) - in Shield to exclude the affected or "already read" notifications by means of the respective period under consideration!

(See screenshot below):

Now I exclude those notifications from my respective view (data table), which were received before the following date: 01/02/20.

###

Additional keywords: notifications, mark read, can not, as read, why not, why can not, as read marked.