Share your experience!
I initially asked this in another topic about the update yesterday and had no idea what the "Assist" option was gone. I'll post the solution below and mark it as solved just in case anybody else has this issue inthe future.
Solved! Go to Solution.
The solution was very simple, I had disabled a system app titled "Introduction to Xperia". As soon as I reenabled that, the Assist option returned in my settings app. I hope this helps out someone else in the future!