The scanning is gone, I just see a bar moving across the screen

Switch Control, Apple's switch-access accessibility feature, works in two different modes:

Item Mode (default mode)

In Item Mode, items on the screen are highlighted one at a time and are selected by activating the switch. The highlighting can be automatic (moving from item to item at a set rate) or controlled by a second switch. With this method, you can open apps, or activate buttons or items that you would tap with your finger. A menu called Scanner Menu appears when you are interacting with items that have more options like sliders where you could increase or decrease the value (for example: to change the volume).

or Point Mode

In Point Mode you can select a point on the screen and interact with it. You select the point using scanning bars (vertical and then horizontal). Once you have selected a point on the screen, you can tap on it, but also emulate other gestures, like dragging, swiping, flicking, pinching, etc. 

Sometimes after and update Switch Control may change into point mode, check this video to learn how to use it and go back to item mode:

Item Mode and Point Mode in iOS Switch Control