I've come to this issue looking for answers about leading zeros in the core string field, where this exact thing is happening (9.5.11). The issue also appears in the address field: https://www.drupal.org/project/address/issues/3017352 → I think the important information is that if the value is currently set to a number and you change it to the same number but with leading zeros it doesn't update. Likewise, it doesn't work going from leading zeros to no leading zeros or two leading zeros to four leading zeros, etc. You can change it to something else (that isn't the numerically equivalent) and then change it to the value with leading zeros and it works. But there seems to be something in Drupal core that doesn't update a field when you the value is the same integer but different strings.