Not sure if this has been reported, or maybe its due to something else.
I think when someone changes their nick, for some reason newer messages from them are never received.
Note that some functions still work, if a user is pinging you, you will hear the sound but never see the text from them.
I found this is true on older versions. The latest git pull didn't display this issue for me. Not sure where the fix was but it looks like its been caught.
Thanks for reporting!