As said above, I go on all sorts of missions, crashed-ufo, faculty missions, ground missions, alien base missions, Enemy VIP missions, Council missions but I can't find a single alien with the "scientist" rank among them. You need to capture an alien scientist if you want to get better weapons and tech and stuff (with the Area51 megamod I have instaled), so going on with the game without it is pretty hopeless. I have a mind-probe tech and I identify every single alien on the battlescape so I'm sure I couldn't have missed any.
So let's see if I've done anything wrong:
I'm running openxcom with 1.0 git 2016-09-25 17:26 nightly version with Area51 mod installed (no other megamods installed, except for the HQ-sound pack with isn't a megamod)
No reason I can think of. Have I not waited enough, have I missed them continuously? Is there a bug or some technical error? Am I doing something wrong?