Hey there,
I might have skipped/forgotten a few steps in the explanation it seems, but I used drag and drop yes 
It seems to not work when just pasting the code into the property (I can’t recall if we thought of that when doing this since we imported a huge list). But create an empty property (file: Create new EMPTY property.png) and do the following:
Multiple contacts:
I had 3000 contacts to update so I imported an .xlsx file with their email adresses in one column, named “email” and the personal code in a column named “the propertyname you chose” (In my example: “Personal image test 01” – file: Example-excelfile-import.png).
Single contact:
To change the contact property of a single contact I found that I had to do it using a workflow (file: Use-workflow-to-change-property.png)
To use it in the email I used the drag and drop field for rich text and then inserted the property through “Insert the personalization token” button (file: dragndrop-richtextfield-insert-personalization token-01.png). It should now look like the file: dragndrop-rchtextfield-insert-personalization token-02.
If you preview this as contact that has this property , it should work
