Screen reader main landmark inconsistent reading

I have a project that has an image as the first item in the focus order of almost every slide in the course. This is important because we need the alt text to be the first thing the screen reader announces on slide.

When testing the scorm in different environments including scorm cloud, and using NVDA screen reader.  The slide sometimes will announce "blank" "main landmark" or both before the alt text of the image. 

The issue is that this is not consistent, while reviewing the file some slides will say it, some will not. The same slide will provide different reads during different reviews or slide revisits.  Sometimes it will read the alt text immediately, sometimes it will say "Blank main landmark", sometimes it will just say "main landmark".

Is there a reason as to way the screen reader is announcing this, and if this is intended why is it not consistent?