I am trying to set an area with items (mkeys) that I don't want to be open to the village, and in order to do so I set the people who are allowed to blue.
I opened my claim, gave full permissions to blue. Then I assigned the people to blue. I opened the field cairn, made sure green (generic permissions) did not have any rights, and set blue to full rights.
The blue members could not interact with it; and when I changed green settings to full permissions (Even though they were still marked as blue!), they could access the chest.
So, it seems to me that field cairns are not updating and are staying with permissions set specifically for green; I even tried changing the color to yellow for them with permissions + stuff but it didn't work.