Zoom Breakout Room Countdown Not Working

I have a meeting with 45 people split into 21 breakout rooms.  The "countdown" option is set to give everyone a 60 second warning when I close the breakout rooms.  However, when I close the breakout rooms, the participants are all pulled into the main lobby with no 60 second countdown.

In the same meeting, after most participants had left, I tested placing 5 people in 5 different breakout rooms.  I did not change any settings. When I closed the rooms, they all saw the 60 second timer and were pulled into the main lobby after 60 seconds.  I have been using breakout rooms in these meetings since November 2020 and the first time I had this problem was last Wednesday.

Any thoughts on how to resolve this issue?  Is it a Zoom bug?