Poor JPEG image quality when Export Image in Animate CC 2018

When I create animated banner ads I have to include a JPEG image as a backup in case the animation doesn't load. The easiest way for me to do this is to select a frame and export to image, however the image quality looks terrible, even if I select Maximum at 100% with Art Optimized.

Any suggestions on how I can improve the image quality?

(I export as JPG since I have a photo in the image. I tried PNG, but it doesn't look any better.)

Also, sometimes when I select "Export Image"  the playhead shifts a few frames when the Export Image window opens. Very odd.

Thanks