I once ran Satan about 15 times before I got an invade. I'd say I usually get an invade within 5 runs on Mythical, so that was just bad luck.
I had a stretch where I went almost 30 runs without an invade across multiple dungeons, drove me crazy. It has settled down since.
0% when you're hunting for a particular one, 100% when it would end your run
This is so true. Ran water and dark dungeons this week, get the invade immediately. I'm sitting on three of each and dont really care about them. Need two light for Neptune and Red Valk, can't get an invade to save my life.