Local sync enabled even though it is deactivated

It’s also possible to store local copies of Albums. Maybe you turned the preference on for each of your Albums. If they have a blue check that means they are stored locally.

Check whether the cloud icon shows that everything is fully synced and backed up.

There is a setting above the setting you mention where it shows how much local storage it uses as a cache for editing. Lightroom CC will keep images around until it hits that point. Only then will it start to delete older image copies. You can also force Lightroom CC to store local copies of all images in an album. In that case it will ignore the local storage settings for that album. The default location for this is inside the library file so you would normally not see them. Are you sure you are not looking at other copies of your images. Lightroom does not delete images from the originating location when you import them. It copies them to a hidden folder and will start uploading from there. Only after fully uploading them and if you are now over the local storage settings limits will it delete those temporary files.

When you add images, Lightroom CC will have to store them locally first. If it did not do that, then you could only add images at the speed of uploading them to the cloud. And if you didn't have an internet connection at that very moment, you could not even add images at all.

After the images have been uploaded successfully, they should be deleted from the local storage.