Stack Rank numbers suddenly messed up in TFS 2013

Question

I don't know if it is related in some way to TFS 2013 Udpate 2 that I performed recently but suddenly many Stack Rank numbers we set manually are messed up and got very high random value.

I have just started using TFS in my daily work and I would like to know if I this behavior is a bug or is considered correct. In the second case is there an option to set in order to avoid this automatic numbering?

Answer 1

Ewald explains everything in this post Behind the scenes: the Backlog Priority or Stack Rank field

After we shipped the change, we have received multiple reports from customers who were confused with the change. If the customer had set the Backlog Priority field via Excel to values 1..N, the old sparsification logic kept the range values pretty much intact (especially the top items). With Update 2 however, once you add or reorder items on the backlog, the sparsification logic sets the field values to big numbers to introduce big gaps, and give you good performance. This change is intentionally, and by design. The Backlog Priority field was always intended to be a system field, and our recommendation is to not update field manually. You can still use Excel to quickly set the order of the backlog with the values 1..N, but be aware that the sparsification will kick in. And although the values are different, the order of the items on the backlog are still the same!

Answer 2

The weird numbers are appearing when you use the keyboard or the drag-drop to prioritize the PBIs. A better explanation is here