Accessibility Alt-text not working on static images

Hello,

I'm working in storyline and the alt-text only seems to work for action buttons. It doesn't pick up static pictures on the slide. 

I'm creating a guided practice which simulates a software environment. So, I take a screenshot of the software page and fit it to the stage screen of storyline. Then I take a screenshot of the button in the software environment that will be the button that the user will click. The trigger will advance the user to the next slide that will have the next screen of the software environment with a button that the user will click, and so on... This will be a guided practice, that simulates the real environment. 

My issue is that the screen reader is not picking up the static picture which is a screenshot of the software page that is fitted it to the stage screen. I have the alt-text applied, with the checkbox selected. I'm using google chrome and the NVDA screen reader and I have also tried the Chrome extension screen reader. Both read the buttons and other interactive fields in the player, but the static pictures that have no interaction are not picked up by the screen reader. Is there something special that you have to do for static images that don't have interaction to be picked up on screen readers?

Just for clarity, the images that have no interaction and the buttons are both images taken from snagit. They are both configure with alt-text the same way. However the static images without interaction are not picked up by the screen reader; but the images that act as buttons, with triggers applied to them, are picked up on the screen readers.