The age might explain it. The longer film remains tightly spooled the more tenacious the “set” of the curl. Film that is stored frozen seems to take more of a fixed “set” than film that was kept at room temperature.

Due to the width/thickness ratio, tightly “set” 120 films are more difficult to load than 35mm. One possible way to deal with it is to reverse roll the film and place it into a lightproof container for week or so before trying to load it onto a reel. I’d recommend keeping it at room temperature to aid the relaxation process.

In this way much of the original “set” may relax sufficiently to load the film onto a reel.