Overview:
A picklist option is not available in Vault for a field that is controlled by a Field Dependency rule.
Root Cause:
There is a Field Dependency rule that is configured in the Base Document type that controls the values that appear in the affected picklist field.
Solution:
There is a Field Dependency rule set up in the Base Document type that restricts what is shown in the affected picklist field based on what is in the controlling field. This Field Dependency rule is populated down to the affected document type because it inherits the Field Dependency rules that are configured in the Base Document type.
The solution is to remove this Field Dependency rule from the Base Document type and redefine it in the appropriate document type.
Related Documentation:
Vault Field Documentation: Managing Dependent Fields