I have a simple suitelet with a form that has select field where the source is subsidiary. I can type in the field and get autosuggestions. But when pressing the list-button to see all subsidiaries, I get nothing. I see in the browser network logs that it makes a call to the suitelet itself and I can see those calls in the execution logs as well. with the parameters q, l, and t. But I shouldn't have to implement a handler for retrieving the valid list options for a field that uses the default source-function? or should I?

Could you show me the suitelet please ?

Figured it out. The script had multiple forms depending on a previous selection. I needed to make sure that the extra list-call by the client resulted in the same form.