Steps to reproduce this issue are as below.
Expected Results: In Steps 7, 8 and 9, the sort column is "Project Manager"
Actual Results: In Steps 7 and 8, the sort column is "Manager". In Step 9, the sort column is "Project Manager". Restore Defaults does not act upon the sort column till we logout and login. Or till the cache is flushed.
This behavior has been reported via DE65339.
Issue is resolved and the resolution will be available as part of 16.1.0
Workaround: Reselect the column that needs to be sorted upon.