Given that this looks to be part of the permanent rolling stock on the ESRI failtrain, has anyone worked out a solution to this that isn't more complicated than simply converting my 200 data-driven page map to a non-ESRI application? I'm desperately hoping I'm just behind the times.
It's not you, it's Esri. There's another whole idea just about fills almost equally as old: Rotate polygon fills in Legend to match Data Frame... - Esri Community
For the "market leader" in GIS, you'd think they wouldn't want bugs and missing functionality lingering for over a decade, but it just goes to show that quality control and usability are not their game.