Slider bug in mobile landscape

Help a sister out!

I have a slider on my page that contains 4 identical (in properties) images. It is working perfectly on all breakpoints except on mobile landscape, whereby images 2 and 3 resize incorrectly, with images 1 and 4 remaining correct. I have a screenshot of the comparison between mobile and portrait here to demonstrate the issue.

The strangest thing is sometimes it works and sometimes it doesn’t! But I don’t want to take the risk of it working 50% of the time.

Here is my site Read-Only:

Here is my live published site: