I also have this problem. I had it previously and decided just to forget about syncing so I deleted extra trees I had created and concentrated on my FTM tree. I decided to give it another go the other day and managed to download my best tree on ancestry to FTM with success and even managed to sync once. Since then if I have tried to sync it freezes in the middle and I have to do a forced quit to get back to ancestry. I agree it is unacceptable and if ancestry sell the product claiming it will do it it should not glitch out so often.