Hello Mark and Nicole!
With the latest update to Storyline 360, which is Build 3.36.21213.0, we've made some enhancements to accessibility.
You specifically mentioned Tab Order, so I wanted to share this documentation which explains it fully.
In short:
- Text and images are read immediately by screen readers so learners don’t have to press any keys to hear the slide content. These objects are read in the tab order you defined in Storyline.
- Use your screen reader's navigation keys (e.g., Down and Up arrow keys) to move through the objects on the slide.