[p1necone]

It might be supported but non obvious, some TVs only support 4k60 through one of the HDMI ports.

It could also be a cable issue, although I believe the option usually shows up on cables that dont support it and only fails once you try to switch.

[asdfk-12]

New cable, tried both ports. The update was the only x-factor.

[Melatonic]

Try setting a custom resolution on your PC and mess with the settings