@gino_m Actually, I tested again and got the same result as you this time. I was wrong about the format that the property editor creates. Before testing the previous time, I added a tag with the editor, the removed it again.
This left this format: tags: [ ]
When I just create properties from scratch using --- in live preview mode, and then add the tags property using the editor, the format is just: tags: with nothing following the key.
When I tested in this condition, no tag was added.