It is not true, a clandestine Mason can be “healed” especially if he joined a clandestine body out of ignorance. Grand Lodges have policies and procedures for this. It may involve signing a document denouncing the clandestine body.
This is a discussion that should be had through the Secretary of a lodge who can contact his Grand Secretary and receive instructions on how to proceed.
The part you said “is not true” is true UNLESS the Grand Master of your jurisdiction “heals” your masonic membership. But that is a big IF. The Grand master does not have to heal anyone. It is at his discretion. And in some jurisdictions he may not have that particular authority.
Just keep in mind when answering that EVERYTHING is jurisdictional. And when presenting answers we need to try to include all possibilities if we can.