All query sorting appears to ignore a leading hyphen, more specifically that and a space after the hyphen.
This affects database and directory queries, as well as QoQ. Demo below uses QoQ because it's self-contained, but it appears to happen everywhere.
Note that a leading @, *, and 1 sort correctly, but a leading hyphen is ignored, with or without a space after it.
Seen in Lucee 5.2.9 and 4.5.5, not in any ACF version I tested.
Windows 7 x64, Windows 10 x64