Yes, I made this test already. But I’m thinking is there any chance security plugin to make the limitations of the writing of some folders or files and for that reason, Jetpack to not write in such folders. Also, may be after deactivation these folders may keep such limitations…
I’m using Jetpack for image optimization because this is the only plugin which works well for me. I tried with other plugins, but with out success. Which image optimization plugin do you use?