Log in to the browser version at lightroom.adobe.com, sign in to your account with your Adobe ID and pw. In the left column look for sync errors and delete them. That is one way clear out the image(s) that are causing problems with sync.
Thanks for the answer; but in the web version I have no synchronization errors (in the left column), in the desktop version continues to look for a photo that cannot be found. In the mobile version everything ok !!! I tried to uninstall and then reinstall the desktop version...but always the same. It’s a mystery.... but Lightroom works correctly.