Hi @Ellen-En-Vincent0, @Andrew157, @Math0,
I've luckily not had this happening to me (yet).
But I've read in other posts, that a small amount of other people are experiencing this as well.
The only thing I can advise is: Install the Airbnb App on your Smartphone. So you will get the 'Airbnb Chime', when a message comes in. And otherwise just have a look at your Airbnb Inbox - at least once a day (Don't forget to refresh your inbox).
It is not uncommon for Airbnb software to contain 'glitches', due to the nature on how they deploy modifications to their system.
So maybe this is one of these glitches?