Broker has pending messages but consumer is unable to consume

[Sangeeth Mukundan]

Hi,
I have pending messages in a queue and it is not being consumed by the
consumers.
This situation happens rarely and sometimes it automatically starts
consuming after 15-30 mins. It didn't change even after restarting the
consumer Nodejs Server
Once this case happened in production and messages were pending for 8 hours
and the Nodejs pod had to be restarted for it to start consuming.
What can be the possible causes and solutions for this?