And by me
(I can't add anything either.)
There is another possibility.
There could be
another blocked link on that page. You can't see it because the error only shows the changes but the blocked link could be anywhere on the page (from another application). It could be that that link is blocked after it was added to the page... making the page completely un-editable.
The only option would be to rebuild the complete page, application by application, until the problem link is found. Or someone with more authority could check if the link is detectable on the current page.