With all plugins deactivated, using the Twenty Thirteen theme, you drag an item below another menu item slightly to the right, save, and it snaps back to the left?
I can’t reproduce the problem myself, which leads me to believe the problem is either related to your installation or browser.
If you really did have all plugins deactivated, try with the Twenty Fourteen theme, just to rule-out any theme-specific issue.
If that doesn’t work, try downloading WordPress again and delete then replace your copies of everything except the wp-config.php
file and the /wp-content/
directory with fresh copies from the download. This will effectively replace all of your core files without damaging your content and settings. Some uploaders tend to be unreliable when overwriting files, so don’t forget to delete the original files before replacing them.
If doubt it’s the browser, but if neither of the above worked, first please make sure that your browser is up to date by visiting https://whatbrowser.org/
If it is not, please try updating your browser or switching to a different browser.
If it is, please do these two things:
1. Try clearing your browser’s cache and cookies.
2. Try with all browser extensions or add-ons temporarily disabled.