English tech description down below:
Nederlands:
In het stukje van postvak-in kan ik geen meerdere berichten selecteren met het menu-item dat hiervoor bedoeld is. Wanneer ik wel meerdere berichten handmatig selecteer en verwijder, dan worden deze in werkelijkheid niet verwijderd.

How did the error manifest itself?
When in the Post menu - I have several messages I want to delete at once.
The menu selector to select all items of a specific type does not work.
After manually selecting multiple messages and using the menu items to remove those. Nothing happens. This is the case for both "buff messages" as for example "reward" messages.

Date and time - When did the problem occur?
When clicking the weekly boat and opening the menu.
9.58 24-7-2021 on Woestewoud

What did you do last?
No previous action. Reproduced the error twice with new login into the game.

Did the problem occur more than once?
Yes

Have you already done the first steps? + Have you cleared your cache and cookies?
Yes cleared history and cookies.

Can you take a screenshot of it?

- please also note the broken graphics showing empty lines although I have a scrollbar as there are more messages down below.


Nothing happens when accepting

Which operating system do you use?
Windows 10

Internet provider / Internet speed
Broadband ~100Mbs - speedtest

Internet access
LAN

Please attach Screenshots of the Dev Console. Please send Screenshots of the "Inspector" tab AND the "Console" tab.
(Press F12 in the browser while you experience the error)


Which browser AND browser version are you using?
Chrome - Versie 91.0.4472.164 (Officiële build) (64-bits)

Also, kindly add reproduction steps, and feel free to add any details you find relevant.
pictures show the full reproduction