Why do the Options AspectRatio and ImageSize not work when defined in SetOptions[DateListPlot … ] ? They work well when defined within DateListPlot or DateListLogPlot.
I tried it on my laptop and got the same result: SetOptions[DateListPlot, AspectRatio -> 1] does affect the list of options returned by Options[DateListPlot] but DateListPlot-s retain their default AspectRatio-s. I believe this is a WL issue to be reported.