This has been a persistent, ongoing bug that the devs have yet to acknowledge. I’ve been documenting this and almost all other competitive bugs since season 34 here:
Please spread the word.
Same thing for me. Not only did I not receive my Top 500 icon from competitive CTF this season and only got the player title, but the career profile stats also removed the proof of me hitting Top 500 in open queue in Season 36 as well. We need to make our voices heard and make the devs give us the rewards we earned.