Been keeping an eye on this today and it looks like Colony Invasion has a bug.
In three straight runs when I have tagged a diplomat to beam out, they do in fact beam out, but I do not get a confirmation that runs across my screen like the other objectives (Data, Colonist). The group also does not get credit for rescuing the Diplomats either. In my next run I will record it and post a video to show what we are getting in case any of the DEVs wanna have a look at it.
There is no bug. If you try to open a crate or use a console or tricorder and you get shot at [Red Alert mode], what happens? It aborts the action. Fact: you cannot do anything in this game while in Red Alert mode except combat. You can't open a crate, you can't use a console... and you can't tag a diplomat. Wait until you are out of combat [Red Alert mode is NOT at the top of your screen]. Also, the diplomat must be standing still [or prone for KDF] and waving his/her arms for assistance. I get perfect scores in almost every Colony Invasion I take part in.
That's cute but there IS a bug. Because the diplomat WILL beam out and still not be counted. For there to NOT be a bug, the diplomat would have to stick around and let you beam them out a 'second' time, or just refuse all interaction until the interacting player's Red Alert combat status was cleared.