Error in notification page

Hello, I have 2 notification in my notification page that I cannot select and/or dismiss.
The 2 notification from The-Art-of-Hacking are not shown in the page and cannot be marked as read or selected in any way.
This situation is ongoing for some days, with the bell highlighted even if no other notifications are present [as for attachment]. I tried also to change and remove notification settings in that repo but everything still remains the same.