Base Layer Information Not Appearing

I developed a 5-Tabs Interaction. I put all of the tabs, the page design, and the page title on the base layer. Then I created 5 layers that contains all of the information for each of the tabs. 

When the slide starts, it shows the "introduction" layer, with the base layer visible. 

The users are then able to select the tabs from the base layer to see all 5 of the layers. 

This is working fine for most people. However, I have at least one person who does not see any of the information that is on the base layer. (see the attached word doc that shows the difference between the developed view & this user's view). 

The biggest issue is the page is locked until the user selects all of the tabs. Fortunately it is 508 compliant so the user was able to use the tab key to move between the layers, but the user never saw the tab titles. Which were also the titles for the layers. 

I need help with 2 problems. 

1 - How do I get the information to appear?

2 - Why is the information from the base layer not appearing for some users, but it is for others? My LMS is Totara which is Moodle based.

Has anyone seen this happen before? Any ideas of the cause? Any ideas for a solution?