you are adding the children to a CNCMill (I am guessing this is the ScrollBox), but then when you go to “display” you are assigning the strings to Local variables in the “picker” function (where is this picker function called?)
if this SlotPicker() is called in a loop then those local variables will only ever hold the most recent thing. which can easily point to everything being repeated, and why for this example you should only see the values of your index 1.
for the Elements you are feeding into your scrollBox, give them like a struct or, members (this would probably require making these elements their own UMG object) then pass in that data directly (take a look at this https://www.youtube.com/watch?v=6CGYprd7vYU )