I Googled Roux and found sites claiming that these 20 consecutive misses came in one game: The January 15, 1948 game between the NY Knicks and the STL Bombers.
can be found what is alleged to be a scan of the original box score. At the bottom, it says Roux's team missed a total of 4 free throws but Roux missed 20 himself. His teammates missed a total of 2, so the arithmetic would make sense if Roux missed 2, not 20.
I looked up the NY Times story on the game, and it says nothing about Roux's alleged remarkable achievement.
At:
https://www.basketball-reference.com/req/202106291/images/boxscore-scans/194801150STB.jpg
can be found what is alleged to be a scan of the original box score. At the bottom, it says Roux's team missed a total of 4 free throws but Roux missed 20 himself. His teammates missed a total of 2, so the arithmetic would make sense if Roux missed 2, not 20.
I looked up the NY Times story on the game, and it says nothing about Roux's alleged remarkable achievement.