The JSON component when used as a LIST does not have a transparent background OR adjustable background at all.
If you insert the JSON component into your timeline & use it as MANUAL, SLIDE SHOW, or CAROUSEL it has a transparent background & you can see through to your other layers. (This is good!)
If you use it as a LIST, it gets a default WHITE background that is not adjustable in any way.
At minimum it would be beneficial to adjust the color of the background to your list.
Regards,
-StarVue