The present constitution was created in violation of the previous Articles of Confederation, which required unanimous agreement to change them. That prevented nothing.
Another way to look at that is that eleven states seceded and adopted a new form of government more satisfactory to their desires. This resulted in the Congressional Register, Vol. 1 (1789) listing the member states by name on the title page.
The Congressional Register;
or,
History
of the
Proceedings and Debates
of the First
House of Representatives
of the
United States of America:
Namely,
New-Hampshire, Massachusetts, Connecticut,
New-York, New-Jersey, Pennsylvania,
Delaware, Maryland, Virginia,
South-Carolina and Georgia.Being the Eleven States that have Ratified the Con-
stitution of the Government of the United States.
Vermont v. New Hampshire, 289 U.S. 593, 607-608 (1933)
In 1777, Vermont declared indepedence. The Supreme Court recognized that Vermont had achieved independence by successful revolution, and had been admitted to the union in 1791 as "an independent state with self-constituted boundaries."
As a practical matter, states have not been sovereign since the expansion of the commerce clause.
The states have not been truly sovereign since the adoption of the 14th Amendment which dictated to states who was a citizen of a state. After the 14th Amendment, states lost the power of self-determination, one of the hallmarks of sovereignty.