I tried Bounce07’s fix and it did not work for me so I thought I’d share what was causing the issue for me.
I had no “Empty Backups Button”
I’m using ShortPixel 3.1.7
Go to > Dashboard/Settings/ShortPixel
Under the Settings Tab “Image Backup” was not ticked after I had Optimized my images.
Make sure this option is ticked
Under the Statistics Tab at the bottom the “Emty backups” button appeared
Hope this helps.
