Same problem with a variance. Update of version on Thursday Aug 13. Next day I had lost half my gold bars (from 410,000) and 39 collections (from 55). Also of the remaining 16 collections all activity had gone. Talked to Microsoft team member but no solution from them. I enjoy playing the puzzles and know exactly which ones are completed and I still have so many gold bars that I don't mind replacing lost collections. BUT IT IS FRUSTRATING. I sympathise with those who have laid out cash and encounter this problem. It may relate to cloud storage and updates to local drive activity. (since collections are all available on line when not connected to internet.) Don't know if this issue will ever be addressed by Microsoft.
Keep on enjoying anyway.