Watermark does not regenerate the same size each time

Hello. We went through and regenerated 1000’s of images the other day. Some of which were skipped for whatever reason or so, and now it is really hard to see what was missed . Today we went in to do a couple that were missed and the watermarks are all screwed up now. http://dev.nationwideelectric.com/product-category/circuit-breakers/page/16/

They should all be the large size watermark. http://dev.nationwideelectric.com/product-category/circuit-breakers/page/18/ Now some are medium size and smaller size like the link above.

Is this plugin broken?????? I have had the hardest time with it functioning correctly. And it takes a full day to regenerate all the images to take the watermark off and then another full day to add them back in.