Power cut out

I am an S gauge guy but I would recommend using a multi meter set to ohms and check for continuity from the section that is receiving power to the section that is not receiving power. Do this with power removed from the rails. Check both the center rail and the outside rail continuity. It may well be that the switch is constructed to allow  storage sidings to be unpowered.

As I watched your short video that it appears the center rail is the rail not receiving power. You might try removing leads from the rails now getting power and try powering the now dead rails to see if you have similar results.

Ray

Ray is right!  That is a good way to Test that Switch!  Appears you have an open on the Center Rail from one side to the other!  The earlier Atlas switches used a very small wire from one side of the switch to the other! All it takes is a SHORT On the track to burn that wire in two!  I replaced that wire on all my earlier Switches before installing them! 
OR connect another “FEED” on the other side!

FREDSTRAINS

Something else to watch for, the outside rails of Atlas track are isolated from each other. When wiring you need to make sure you keep the common on the same outside rail throughout the layout or else connect the two outside rails together. This can also cause a loss of power like you are experiencing.

Not exactly related to power loss, but since you are using DCS, make sure you isolate the center rail in at least two places per loop (creating two isolated blocks) and feed each isolated section with a separate power feed from a central terminal block. Also, isolate your loops in the same way between the cross over switches. Wiring my permanent layout this way (per Barry's book) has eliminated all previous DCS problems I had on every small temporary layout with no blocks. That is, all but the operator induced problems, I'm working directly with the operator on those...