Accented characters pop-up not working

Hi,

I am using a MacBook Air on MacOS BigSur version 11.5.2

I would like to have the option that when I press and hold a letter, e.g. the "E" that a pop-up appears that allows me to choose an accented character. I have tried everything I could find related to this topic to get this working, but unfortunately to no avail.

What I have tried:

• removing and reinstalling keyboards
• selecting an "international" keyboard and removing that again and replace it with a Dutch keyboard
• resetting the standard settings in the keyboard preferences

executing the "write -g ApplePressAndHoldEnabled -boolean true" command in terminal and rebooting my machine afterwards

I even checked if ps -ef|grep PressAndHold includes a line for /System/Library/Input Methods/PressAndHold.app/Contents/MacOS/PressAndHold and did a run open -a PressAndHold.

I also did  killall PressAndHold;open -a PressAndHold 

• Finally I deleted ~/Library/Preferences/com.apple.HIToolbox.plist. Normally defaults read com.apple.HIToolbox should show com.apple.PressAndHold under AppleEnabledInputSources and AppleSelectedInputSources and it does on my machine.

In short: I am at a loss. Who has additional ideas to get this fixed...?