A couple of races ago our league had a race go wet towards the end. My automatic tire strategy is set so that my cars will get Full Wets if it starts raining and there is 0mm of water - I had it set to 1mm before but it took forever for the cars to pit because of how long it took the track to get 1mm of water coverage. I want my teams to pit as soon as it starts raining for wets and that was the only way I could figure for it to work.
Well, it started raining and my cars immediately dove for pit road just like I wanted them to - except they remounted softs instead of putting on wets. Since I was in the lead by a healthy margin at that point, you can imagine how irritated I was. I finished the race on softs and lost both the lead and most of my available points.
On a somewhat related note, I noticed that as my car went slower and slower on the wet softs, when I hit KERS the car suddenly behaved as though the track was dry - my overtaking speed was as fast as it would be if I had hit KERS on a dry track, in other words.