Presentation slide image won't display right

I started up another website using HighEnd Presentation. I tried to change the background image on the presentation slide and couple of things are not working right. First it won’t let me pick the image from the media library. Only way to pick it is to upload it from my computer and then it lets me insert into page.
Secondly once I did that, the image displays very very grainy.
I imported it into another page in a slide show and it looks ok there. It looks bad on the presentation slide though.
I have upgraded to WordPress 5.0.3 recently. Is High End Presentation not compatible with 5.0.3?
What could be the problem?