Silly question for you all. What is the expected value for a checkbox in a suitelet? It seems it doesn't like boolean. Is it "true" / "false" or "T" / "F"?

It’s a little crazy. If your’e reading the value from the page in a client script running on the suitelet, it returns Boolean. If you’re attempting to set the default value when creating the form, it is “T” or “F”, and when you’re reading the value from the posted form data, it’s “T” or “F” or “” (if it was never set)

Yeah, it was pretty easy to fix though

this is a good argument to not build UI suitelets for the most part.