Sorry to hear of your experience @artyberty. While I didn’t see a support topic form whereby we could assist, I would be happy to work with you to try and determine what may be happening.
One possibility is that the images you are uploading may be already optimized, and converting them to AVIF or WebP may not reduce the file size, in which case such formats won’t be generated. Alternatively, your host may not support AVIF images if this is the format you wish to use. If AVIF is the format you wish to use, and it’s not support by your webhost, this will be highlighted in your media settings (Settings > Media).
Another possibility is that you’re looking to convert existing images. The plugin will only generate WebP or AVIF versions of newly uploaded images.
If you’d like to share more on your experience I’d be happy to assist. Feel free to share an example image that doesn’t result in a WebP or AVIF version generated and I can perform some checks, or share your Site Health information here or privately via this form so I can check your environment.
I take your point on board regarding documentation also. The Core Performance handbook has more details on the overall Performance Lab plugin and not specifically Modern Image Formats, but there are resources on there so share such feedback or to take part in weekly discussions. I’ll pass on your feedback regarding this.
Let me know if you have any questions with the above.
