Gform_user_ registration_meta_value return empty value

I create a form that creates users pending activation. When the user registers, they complete a series of check boxes whose content is right when reviewing the entry in Gravity Forms entries list. The user remains pending activation.

I use the gform_user_registration_meta_value hook that is fired when an administrator approves the user. When the user is approved, I generate some logs in the debug.log file to see the value of the hook’s first parameter ($value).

In my form I have 6 sets of checkboxes. The first comes complete, as a string of values separated by commas. For the second checkboxes group $value only brings the first value. For the other 4 $value parameter of the hook is empty inside the function that triggers the hook and I don’t understand why, because, as I said, when I open the entry record in Gravity Forms, all the data appears correctly.