The are multiple reasons for no new messages coming from the server:
 - network connectivity problem,
 - few suggestions (e.g. for a weird country / language combination),
 - user has reached a server-side limit.

The client should show a hint to the client that it is WAI when nothing new appears. For instance a toast message along the lines of 
"There are no new items there right now, but might appear soon".
(the text needs some UX love)