Hi,
thanks for your message.
Basically the way to do it is like this:
1) go to Settings/ShortPixel and change the compression setting from Lossy to Lossless (or viceversa, not sure what option did you use already)
2) make sure the WebP option is also active
3) bulk optimize all the images again. At this step WebP images should be created
4) go back to Settings/ShortPixel and change the settings from Lossless to Lossy (or viceversa)
5) again run Bulk ShortPixel
I realize that this is not the most elegant solution but currently that’s the only one available.
If you need further assistance please don’t hesitate to contact us directly here:
https://shortpixel.com/contact
Thank you,
Alex