Xbuntu / AMD
Short description of error
If you toggle on the alternative start/end frame range it give you a dark overlay in the Dopesheet Editor to indicate an alternative start and end. However when you go to the Graph Editor it doesn't show it there.
Exact steps for others to reproduce the error
Change the Viewport into the Dopesheet Editor
In the Timeline, toggle the Alternative Frame Range button
Set the start and end frame to something else (25-50 for example)
...you'll see the dark indication at the start and end frame in the Dopesheet Editor...
Go to the Graph Editor
...it still thinks the original frame range is being used...