Same thing just happened to me. Lost everything but the level I was on. Game would not open on iPad. From the responses from King their attitude is really disappointing that they really don’t care about loosing all the boosts.
I hate the game now. Very much not fun anymore. Have been going into the App Store looking for a replacement game. Still going into cc to get the free boosts and waiting to see if King comes to its senses.
What I see is if you back out not only so you loose a life you also loose the selected boots. I made a mistake and went into a level with boosts checked. I did not do any moves and immediately backed out and had one less of each boost