1-In the slider’s Row settings > Design > Background image position, select ‘cover‘ instead of ‘auto’ so the image will fill up all the slider width.
Even in your third slide, the image seems to be more square than the slide’s dimensions, however if set to ‘cover’ it will adjust to fit the screen. I changed it in slide 3 for demonstration.
2-There seems to be some issue indeed with 4th, 5th and 6th slides. I suspect some shortcode has gone wrong. I suggest you remove them altogether and add them again by just cloning the last slide(number 3). I tried it and as you can see slide no 7, is showing ok.
