polari drops certain chat messages
I don't know of any way to reproduce this, but sometimes polari drops chat messages sent to me. The unlucky dropped message appears only in the GNOME Shell notification but not polari's chat window. This makes it impossible to see the message after the GNOME Shell notification disappears. It's frustrating because notifications are nowadays only visible for a few seconds.
When this happens, the messages sent before and after appear normally in polari. Only one particular seemingly-random dropped message will be missing from the conversation.