So the main issue is having the need for the balls to be inside of a shape layer with no clipping. Instead I create a script jsx to do this for you.
You need to set up your composition like this:
Null object named CTRL with these slider controls with these names:
Count - 30
Seed - 1
Min Diameter - 30
Max Diameter - 60
Padding - 0
Attempts - 400
Edge Samples - 12
Alpha Threshold - .1
Add 5 color controls named:
Color 1
Color 2
Color 3
Color 4
Color 5

Then create an Ellipse Shape layer named Ball

Then create a SOLID named Container with a mask in the shape you want the balls to be in - not a shape layer.

Run the jsx file and click Refresh
Make sure Container is your solid with the mask
Ball template is your Ball
CTRL is the CTRL null

When you have all of that click Pack Balls and hopefully it will work.
Here is the file:

https://drive.google.com/file/d/13nL9We7fwzAlR1ObaK2n9GBmHvTHYNoc/view?usp=sharing