SYMPTOM
The sort order applied for an attribute is lost after swapping in Dossier in Strategy Web 10.10
STEPS TO REPRODUCE
Follow the steps below to reproduce the issue:
1. Create a Dossier based on an Intelligence cube, add an attribute to Rows and sort Descending:

2. Click Swap, note that the sort order of the attribute elements get lost in Column:

3. Continue clicking Swap, note that at the 3rd time, the sort order in Rows get lost and the sort order is missing from Advanced Sort window:

CAUSE
This is a known issue in Strategy Web 10.10.
ACTION
Strategy will continue to investigate and post updates as soon as they are available.