Xbox 360 game on backwards compatible not recognising game pass ultimate and not letting me...

Game Pass Games are subscription based games, and only Backwards Compatible 360 games for the Xbox One work with Game Pass.

If you have Game Pass Ultimate, which includes Gold, you can keep the Games With Gold for Xbox 360. But with only Game Pass, you can't play any backwards compatible games on the 360, and on the Xbox One, the games stop working after your Game Pass trial
ran out.

So in short: No, you can't keep Game Pass Games, be it Xbox One or Xbox 360 games. And Game Pass doesn't work on original Xbox 360 consoles at all.

The "Backwards Compatibility" only exists for games that they have told the XBox ONE to recognise as "Backwards Compatible".

Most of the games on the XBox 360 simply will not work on the XBox ONE.

Microsoft will claim the reason they can't make everything available at once is that they need a Publisher's permission to make the game Backwards Compatible.

But the real reason Backwards Compatibility exists is to lure XBox 360 owners who have been on the fence for a while into the false supposition that they will be able to play their 360 games on the ONE.

If you could do that... why not buy a ONE?

I understand, as this is an Xbox 360 game that is used via backward compatibility, it requires an active Game Pass standard, Game Pass Core, or Game Pass Ultimate subscription.

Additionally, you must sign in with your Xbox profile and this will allow you to play this game online

From what I heard, Xbox 360 kinect games will not be available on the backwards compatibility due to the Xbox One kinect being different to the xbox 360 kinect, and as such the game wouldn't recognise it.

What game are you trying to play?