by Mary Cooch.
Hello there
Sorry for the delay replying; I came to this via a recent forum post of yours. Can you replicate this behaviour one one of our demo sites - for example - http://school.demo.moodle.net/ ?
You can use the manager role to ensure the teachers cannot "access all groups". If you see the same results, I suggest you report this in the tracker https://tracker.moodle.org (I will go there myself and see if this has already been reported.)