Symptoms
List Items not showing up in edit view on Initialize
Diagnoses
We compared the working and non-working versions of the solution, and determined that the input for the List method that loads data on the List View was coming from a View parameter that gets filled on Form Initialized via a text box on another view. The other view was being loaded asynchronously, so the following rules fired off before the text box had a value.
Resolution
Changed the asynchronous calls to synchronous 'then' statements.