You added a new created extension field to e.g. Utilities - Customer enterprise search category and are expecting that this field becomes visible on Utilities > Customer Search list view advanced search. However the field is not visible to be added on that view.
SAP Cloud for Customer.
Once field is added to enterprise search, it will appear under respective category of the enterprise search and not on advanced search of a list view. If a field has been created under e.g. Account - General Information business context, it will only appear under Utilities - Customer Search view if there is a respective extension scenario enabled.
To add the field on advanced search, you need to check if there is an extension scenario to attend his needs.
Enterprise Search, Advanced Search. , KBA , AP-RC-UIF-FLX , Page Layout & Key User Configuration , How To