Hi there,
Thanks for reaching out!
The plugin will only compress images that have not been compressed with the plugin before. Once images are compressed, you do not have to compress the images again.
If you want to optimize images that are not compressed before, you can use the Bulk Optimization tool. In your WordPress dashboard, hover over?Media?and select?Bulk Optimization. This will take you to a screen where you can compress all the existing images in your media library.?
If this does not answer your question, can you please send us an email at [email protected] letting us know what your Tinify account is and screenshots of your issue?
Hope this helps!