[Bug] Diplomacy/Envoy

I read a post about this issue in the .62 version, but i have the same issue in now in .76.  After sending an envoy to all of my ally's planets, he still sends me a mission to send him an envoy...but when my second envoy gets to any of his planets the mission clock continues to count down.  I can't complete the mission!  In the end this is only a minor annoyance, but it still needs to be fixed.