Other things you can try:
Menu -> Extensions -> Extensions and disable any extensions you installed to see if one is the culprit.
If you have Opera's VPN turned on, try it with it off.
If you have Opera's adblocker and tracking protection turned on, you can click the icon in the address field when on netflix.com and turn them off for the site to see if that helps.
Menu -> New private window to see if things work fine there.
You can test in another browser like Vivaldi. to see if it has the problem also. If so, it might be something outside of Opera that's causing the problem like some security/anti-virus software you have.