The set theory of the 1940 first edition of Quine’s Mathematical Logic married NF to the proper classes of NBG set theory, and included an axiom schema of unrestricted comprehension for proper classes. In 1942, J. Barkley Rosser proved that Quine’s set theory was subject to the Burali-Forti paradox. Rosser’s proof does not go through for NF(U). In 1950, Hao Wang showed how to amend Quine’s axioms so as to avoid this problem, and Quine included the resulting axiomatization in the 1951 second and final edition of Mathematical Logic.
So I was wrong—the fix came only one decade later.
Quoting Wikipedia
So I was wrong—the fix came only one decade later.