unsure as I have never used the auto save feature.
Are you sure that you have it enabled? Try unticking it, saving the settings, and then reticking it. Dunno, long shot there but not sure.
Are you sure that you're completling the race? afaik auto save replays only save once the final race position's are in! (not 100% sure of this one either)
Yeah, I tried all this after you mentioned it. But it only saves sometimes. I tried the manual save option but it doesn't give me a choice to save the race when finished.
I don't recall having any problems before this patch, tho. However, I disable auto save for feature races. Never had problems enabling that feature either.