I have Moodle 3.4.1+ (Build: 20180223) and use bigbluebutton (v2.1.14) plugin with isolated groups feature in order for students to see only records within the group they belong to.

After upgrading BBB plugin to version 2.2.1, all students could see recordings of other groups they don`t belong to.

I had to downgrade to BBB plugin v2.1.14 to keep this feature working.

Some screenshots:

1) before the upgrade

http://prntscr.com/ij4arh

http://prntscr.com/ij4avm

2) after the upgrade

http://prntscr.com/ij48k7

http://prntscr.com/ij48t3

I believe Moodle version is not the cause of the bug, because I used moodle 3.3.2 before upgrading to 3.4.1. And the situation was the same: students began to see all recordings after switch 2.1.14 -> 2.2.1 BBB plugin, even on older moodle version.