Ok the issue is primarily caused by the file browse item and the combination of several settings.
After applying the changes the "allowBlank" config is set to null for the file browse item (I don't know why and is a bug) with this null value or a false value means that the file browse item requires a value. This then causes the form to be invalid when the form load is fired i.e. a "value required" validation failure is shown for the file browse item. However a form load should not trigger a validation so I need to investigate further.
Since you checked the "wait for result" on the form load dynamic action the form load is not actually fired since the form is invalid therefore subsequent dynamic actions do not fire (this is expected behaviour). So this is the reason your window does not show.
To workaround this
1) uncheck the "wait for result" on the form load dynamic action OR change the display sequence and have the window show come before the form load.
Note: I have already applied this to your example oon page 218.
I have logged a bug for the file browse item validation issue.