Option to disable adding covers from MPLS playlists

After upgrading to the latest release I only found out by chance that MKVToolNix started to add covers from MPLS playlist sources. This is an unwelcome change for me and so far I have not found a way to turn this off. Removing the item type "attachment" form the list of items to copy did not help.

Can you please add an option to turn this off or enlighten me where to find the option?