After fiddling around with it a bit I have found out that it appears to occur if you sort by newest first.

I opened a new incognito window on Firefox, selected any filter (or no filter), sorted by newest, and the list becomes stuck sorting backwards and does not fix itself upon sorting by oldest. If I first sort by oldest then the ordering works properly.

It must be the filters that mess with the ordering because when I select a few filters then sort by newest or oldest it seems to be incorrect.

I believe that the oldest/newest sorting is backwards and there is no filter for Canada.