I previously had drag & drop to permanently re-order working about 2-3 weeks ago, but it is no longer functioning. I can’t fathom why unless the data has become to complex for the plugin, but it feels straightforward?
A mockup of the table in the most basic sense is below. Is there any reason this setup would break your drag & drop re-sort indexing?
The UI would basically Show Bob who is presently managing Project A the ability to sort Common Title of Thing 1 and Common Title of Thing 2, but he would not see things of the same textual name for Project C within his current view and is only indexing/sorting against those in project A (unique ids behind, but the text titles of each are common).
Not sure the 1,2,1,2 depicted here matters much, so long as the sort order is relative to the items in each project behind the scenes.