Guild Wars 2

Many times I see the message (see attachment) after the actual events have been completed and as far as I can tell, the reward has been given.
It happens all over the world and with missions I had 100% participation.

It has been that way since around HoT was launched, I just got used at it and make jokes when it happens :P

It’s a known bug with a very low repair priority. The bug is a result of a bug fix that rolled out just after HOT that was meant to delay event time-outs (previously you could time-out of an event just because the event had a 30 second pause in the killing!) It doesn’t impede game progress or prevent you from getting rewards, and the dev team has a LOT of more serious bugs to stomp on before worrying about this.