Is it possible that this issue results from the fact that I do my reviews on AnkiDroid?
I am using AnkiDroid v2.16alpha97 with the new backend and v3 scheduler enabled. However, I have come to realize that it doesn’t behave similar to Anki v2.1.61 in all aspects (though it does in most aspects).
A similar issue was reported here before the Review Sort Order setting was added to Anki: Maximally spaced filtered deck order