Marketpress pictures

I have a couple of points to bring up that I hope you can help with.

I’m using Marketpress on one of my sites and the picture quality in the display picture is very low and bitty. When I use the same picture in the Learndash course software I’m also using it is a good quality output. They are jpeg images.

Is there anything I can do to improve the quality in of the pictures in the Marketpress plugin?

I also tried to upload png images to the main media part of wordpress and every time it fails to load and be saved in the media section. Any ideas as to why it fails?

Thanks in advance for any advice