Previous button doesn't work in view 'Step-by-step' recording

Hi there

Having some problems with Previous buttons on my course.  The irritating thing is that it only seems to be a problem in one scene, not others. (And for the life of me, I can't see any differences between the scenes where it works and this problem one...).  

There is a view step-by-step video in the scene.  The scene starts with a static slide and then goes into the video.  The slides (except the first static one - they must click 'Next' to proceed to video) are set to automatically advance at the end of the timeline (as is generic for step-by-step).  The first 'Previous' option (i.e. going back to the static slide) works.  However, when the user clicks the 'Previous' button on any slide within the step-by-step, it doesn't go to the previous slide (or step), but rather 'restarts' the current slide (step).

I have looked at various threads on here and so far have tried:

• Linking the previous button to specific slide numbers instead of the generic 'previous slide' - no luck.  
• Removing all the 'previous' triggers. (This was in hope that the generic in-built previous settings would take over - no luck).
• Removing all the 'previous' triggers and adding them again (using the generic 'previous slide') - no luck.

I don't have a menu on this e-learning course, so navigation shouldn't be an issue (it is set to 'Free' anyway, I checked).

Any ideas?  I need to fix this for my client.  I also unfortunately cannot upload the file due to confidential information on the course (and it's probably too big as well...).

Any help is greatly appreciated.

Kind regards

Robyn