The fields are located in different tabs with different access levels

The fields are located in different tabs with different access levels. When entering in one field, it is not possible to overwrite in another. Auto actions settings - triggers user update and update user, field 1, set (field=value), [field 2]. Is the reason for the different access levels of the tabs? Is there any way to get around this? Thanks

Not sure I understand. You mean your field auto action isn't updating a field? Tab access is irrelevant for the auto action. Please provide a screenshot of your global and condition parameters for your auto action.

The original field [snils] with the access level to the Access tab 1 (this level is disabled for the user). The user must overwrite the source field through the [snilsfisfrdo] field located in the Access tab 2. The condition is a non-empty source field.

The [snilsfisfrdo] field is being recorded, but there is no overwriting in the [snils] field.

Your auto action isn't published in your screenshot so it's never going to trigger. Ensure both the auto action and CB Auto Actions plugin are published. If still not working the enable debug mode in Joomla global configuration then under Parameters of your auto action enable debug. That will let you know if there's any errors happening, if access check failed, or if condition failed.