The Obama thing doesn't surprise me because progressives often accused Obama of not being progressive enough (he wasn't).
That chart doesn't show that Sanders voters who voted Trump turned out to be Republican. Only 5% were strong Republican vs 10% strong Democrat. There's a lot more not strong dems and lean dem voters than not strong and lean republicans that voted Sanders-Trump.
Combine those numbers with how many strong, not strong, and lean dems that didn't vote at all and you have the bigger picture.