It was removed during Murkmire.

Patch Notes: https://forums.elderscrollsonline.com/en/discussion/444457/xbox-one-patch-notes-v1-14-0-0-murkmire-update-20#latest

Here's the Overload Changes:

"Overload:
This ability and its morphs no longer grant a third ability bar when toggled on.
Weapon abilities can now be used while in Overload mode, and are no longer hidden.
You can no longer generate any Ultimate while this ability is toggled on.
You can now toggle this on when you have 25 Ultimate or more, previously 75 Ultimate.
Light and Heavy Attacks are now off the global cooldown and can be woven with other abilities.
Decreased the damage of the Light Attack by approximately 50%.
Increased the damage of the Heavy Attack by approximately 60%.
Power Overload (morph): This morph now specifies the bonus range and radius for the Light and Heavy Attacks.

Developer Comment:
We want Sorcerers to feel like they have access to their full arsenal while in Overload mode. This ability is updated to better integrate with other abilities. As soon as you Overload light attack you can cast an ability, just like the light attacks of any other weapon set."

Don't think we'll ever get the third bar back. I don't mind though, every other class has two, sorc should as well.

What I would like to see:

1.) The ability to slot a pet on one bar and not need it on the second.

2.) Streamlining of sorcerer class skills by folding the less useful skills/situationally useful skills into others.

My back bar is full of buffs/shields. Half of my front bar are debuffs (one dot). I have TWO offensive skills (half of which can be reflected.)

Feel like magsorc is the hardest class to play since you need a bar and a half of life support skills to not get destroyed immediately.

*Confirmed. Just hopped on my dk and it's easy mode. Don't even know how to play the class and got more than 10 kills outside sej. While on my sorc its like im like limping around Cyrodiil with two broken legs and a concussion.*