Sorry for top posting, I am not subscribed but was this since I am having a similar issue. Basically, 1.20 did not work for me at all on RM520N while 1.23.8 and newer will throw a cancellation error but in reality the modem gets unlocked and is usable in a couple of seconds.
https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/issues/919 Regards, Robert
