538 had a 30% chance of Trump winning. Here’s the last analysis prior to the election. Of my friends following politics at the time, I was the only one who thought Trump had a chance and was slightly worried explicitly because I was following 538.

https://fivethirtyeight.com/features/final-election-update-theres-a-wide-range-of-outcomes-and-most-of-them-come-up-clinton

Edit: I reread your comment and realized you meant specifically the scenario where Clinton won the popular vote but lost the electoral college, but Mr bronze’s model gave that scenario a 10.5% chance if you look at the bottom of the final 2016 forecast, and it’s also mentioned briefly in the analysis I posted above