did you open the CSV in excel or similar and let it reformat the data to your locale? (this happens to me, it shows as d/m/y)
when I look at the raw CSV I see it as 8601 already:
(this does remind me I still owe the forum a big date/time/datetime comparison in lookups / defaults / date math / choice vs CSV vs entity across collect/WF/Enketo as I also hit some hurdles there before)