“An active PHP session was detected”

WP 6.7.1

Also seeing the “An active PHP session was detected” message in Site Health, which disappears when the plugin is disabled.

Also, the plugin seems to be working, in that the focus point can be seen in images and I finally found how to set it too (though it’s pretty involved!). But now… what? The description sounds like the cropped thumbnails will be autogenerated, but… I don’t see anything happening.