Captivate 9 breakpoints not showing correctly on LMS

Hello,

Using Captivate 9, I have set the mobile device breakpoint to 320 x 480. (I have many employees with different types of cell phone, so I'm not designing for a fixed breakpoint - so I thought of using the smallest breakpoint).

When I preview - either Scorm Cloud or Inspect, everything (the images, the text size ) renders fine.

However, when I do the course on my iPhone (which is a 5S), the text box is no longer appropriate size - It's too small. For example, instead of seeing on my iPhone the following text "Hello, my name is Peter". as I see on my captivate file... I see "Hello, my name". The text box has resized.

Is this because my LMS is already responsive, and somehow, it doesn't take into account my course already being responsive?

Just not sure how to proceed to make sure everything fits well when using a mobile device. This course has to be responsive as my course targets on the road sell reps.

Any suggestions?

Many thanks,

Julie