If I were you, I would try creating a list variable and populating it with an Update Data action, then use it in your Dynamic Slot. Then, as Jason said, you can use Replay mode to examine what is going on (including exactly what kind of list is being created!
In general, I find it's best to not try to do too much in a single hit.
If you did this, you would find that the collection being created by MakeList(SchoolList) is creating a list with a single value (your string) in it, not breaking it apart using the commas, as you expect. I would investigate the Split() function, as this breaks a string up based on a delimiter.
HTH
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Paul Simpson
Views expressed are my own and do not necessarily reflect those of my employer.
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