Selectively presenting n number of random images from a bigger list

URL of experiment:

Description of the problem: Trial → “Selected rows” does not present the images I declared in a variable containing the list of images.
I wrote a js script to randomly select 55 items out of 110. Save these indices in the variable ExtraFeedbackItems. And then I use this variable in the SELECTED field of trail.
Instead of presenting 55 items it is presenting the whole 110 items.

Any help is appreciated!