Hi. WebP Support in server is enabled but I have the same problem. This plugin perfect worked in my Hosting. I transferred wordpress site from Hosting to VPS and don’t works now (obviously this is due to server configuration). File .htaccess has the rules for webp above the line reading #BEGIN WordPress, but then I try to activate Images to WebP again I see the same instruction.
Can you show me response from @kubiq which helped for you?
PS. webp is already the newest version (0.4.4-1) and enabled