Participants cant hear each other in break out rooms but can, in main room. Any Pointers??

[ActiveLearner]

Hello ZOOMERS,

We are having this issue and no idea how to go about it. Few colleagues have complained that when they add participants of a meeting to a break out room, the participants cannot hear each other but when they are back in the main room, then they do hear each other... I have never encountered this type of issue before... any help will be appreciated.

Steps I have adviced colleagues so far: 
1. s to tell participants to make sure they are using the latest version of the app.
2. To make sure they have a stbale internet connection
3. to ensure they have the right audio settings

Colleagues uses Dell windows with zoom version 5.17.29
thanks