Why can't I order by rank, even though I've ordered by rank?

[leewarren]

[Nic Brough -Adaptavist-]

The error message is referring you to the board filter, not the search/narrowing/quick filters you have in the screenshot.

(edit - sorry, hit post too quickly).  You'll want to go to the board configuration and in the first general tab, check exactly what the board filter says to order by.  It needs to end with "order by rank" or "order by rank asc" and no other fields should be in the ordering.