Thanks Nedim, it was a rookie mistake not making sure I had the next button selected in the slide properties. I've got that fixed and the next button is now on the questions. I have another coworker that will be putting feedback in and will need to make sure that works correctly when they're done with their work.
You do not need to add the NEXT button via the Slide Properties. In fact, when you do that, the NEXT button will always appear next to the SUBMIT button on the questions. And that could confuse users. Someone could advance without submitting their answer. And they'd have to way to return to unanswered questions, unless you also include the PREV button.
FYI: Adding the PREV and NEXT buttons—and deselecting the SUBMIT button—is done for quizzes when you want to let the user submit all of their answers at once. In those cases, folks typically add an extra slide before the program goes to the Results to remind the user that they should ensure they have answered all questions before proceeding. Here's more info: Submit Answers All at Once in Storyline 360 - E-Learning Heroes (articulate.com)
The reason you couldn't advance from the Correct or Incorrect feedback layers is because your custom layout doesn't include the "Button" placeholder. Storyline uses that placeholder to add a Continue button. On the Correct or Incorrect feedback layers, the button is automatically given triggers to hide the layer and to jump to the next slide.
BTW, Storyline automatically adds the PREV and NEXT buttons to a Question slide when the Review Quiz or Retry Quiz triggers are needed. That happens even when those buttons are deselected in the Slide Properties.
