Zoom chat disappears when people return to the main room after closing the break out rooms

Hello, 

I was hosting a meeting some days ago and opened some break out rooms. When I closed the break out rooms and people returned to the main room,  they notified me that they could not see the chat messages that they could see before entering the break out rooms. 

Has anyone noticed this before? Is there anything I can do to make the initial chat messages be visible for people after returning from the break out rooms? 

Thank you!