Security options don't apply in breakout room

Hey everyone. Yesterday we experienced a big security problem in our meeting. I tried going through all the settings (in Zoom and online), but I can't seem to find a solution. I hope you can, thanks!

For our meetings, we don't want participants to be able to unmute themselves during the program. Fortunately, there's a setting for that, which we used.

Now in the main session, it worked, nobody was able to unmute themselves. But in the breakout room? Oh boy. A visiting participant kept (unwillingly) turning on his mic. The co-host had to manually mute him every time.

Afterwards we did some testing, because we thought the problem was that we made the breakout room before we applied the security setting. But nope, if we made a new breakout room while the setting was turned on, it was still possible for people to unmute themselves there. We also checked if there are separate security settings in the breakout room, but nope.

So like the title says: the security option of not allowing participants to unmute themselves does not apply to breakout rooms. Help, what do we do? Thanks!