Hey there, the original poster here
You seem to be having an unusual issue. In my case, all functions related to the ambient light sensor were missing on my computer (not only True Tone, but also the backlit keyboard and automatic brightness), so I figured it was a hardware issue with the ambient light sensor. I tried every possible method to fix it but to no avail, so in the end I had to hand it over to an Apple Store for it to be fixed from the ground up (Everything is working fine now. My computer was still under the 1 year warranty so I didn't have to pay a cent)
But in your case, the True Tone toggle is missing, but you still have the toggle for automatic brightness, so it can't be an issue with the ambient light sensor. I would advise you to wait for the next software update and update to it once it comes out, as it may be a software-related issue. Sorry I couldn't help you in any other way