Hmm, what browser are you using? Some browsers don't support newer video formats or quality options. If it’s not your browser, we'd recommend running a quality report on your ISP as a next step: https://yt.be/help/iuLB . Hope it helps!
It seems odd that it's working on incognito–try logging out > clearing the browser's cache & cookies > log back in to your account, usually, that fixes the issue. If it still doesn't, you can send a feedback report w/ these steps: https://yt.be/help/feedback .