Watermark Applies to Some Images

Hello! Good work on your plugin. I like the watermark when I can get it to work. On my most recent post, the watermark was applied to some images and not others. Is there something I should change in the settings? Thanks in advance!
Automatic watermarking on
Manual watermarking on
Enable watermark for featured featured-medium gallery large medium
Check image sizes on which watermark should appear. on selected post types only. post
Automatic frontend watermarking off
Plugin deactivation off
Watermark size scaled
Image format baseline