Board Game Arena

Whenever I play a specific player & win, I receive 0 ELO points every time... I mean every time.
I know how ELO works, but would someone please explain why this happens?

Consecutive win penalty. Not "whenever", but after you have won (and never lost) the last 6 games against that player. I think the memory resets after 7 or 30 days (reports differ, it may be different for each game, or it may depend on other things).