Product Hover Effect on Overview Pages not working after Image Optimization

Hi,

The “Product Hover” feature (which can be found in the Edit Product Section of each WooCommerce Product)

does not work after optimizing the first image of the gallery with ShortPixel.

The products, for which I did not optimize the Hover Image, the feature works fine: not optimized hover images
However with the other ones; e.g. these image optimized products, it does not work anymore.
(I am more or less ruling out, that this has to do with Cache, since it is working for the ones and not the others (and has been that way for a couple of days now. I think, it somehow has to do with what ShortPixel does to the images..?)

Since image optimization seems to be quite vital for good page performance, I would of course prefer to optimize all my images, without sacrificing the Product Hover Effect. I hope you can help me with that.

Thanks in advance for your answers.
Best Regards
Alex