BLE Characteristic Read By Connected Client

Question

Hello, 
 I have a BLE peripheral device that becomes the server once a connection is established. The BLE services and characteristics are all custom, I will include the defines below as a reference. What I am having a problem with is the data sent when a read characteristic is done by the connected client. Where is this data retrieved from on the peripheral/server side? Basically, where is the local database storage on the peripheral that is referenced by the connected client? 
 I was assuming I could just load the correct data in the buffer during a specified read callback, but that doesn't seem to be working correctly. 
 Below are the services and characteristics being used, the one I have a problem currently using is: BT_UUID_MOBILE_APP_GENERIC_UTILITY which has both BT_GATT_CHRC_READ and BT_GATT_CHRC_WRITE_WITHOUT_RESP characteristic capabilities.

// Custom Services and Characteristics Declarations 
 BT_GATT_SERVICE_DEFINE(mobile_app_svc, 
 BT_GATT_PRIMARY_SERVICE(BT_UUID_MOBILE_APP_SERVICE), 
 BT_GATT_CHARACTERISTIC(BT_UUID_MOBILE_APP_DATA_OUT, 
 BT_GATT_CHRC_NOTIFY, 
 BT_GATT_PERM_NONE, 
 NULL, NULL, NULL), 
 BT_GATT_CCC(data_out_cfg_changed_callback, BT_GATT_PERM_READ | BT_GATT_PERM_WRITE), 
 BT_GATT_CHARACTERISTIC(BT_UUID_MOBILE_APP_DATA_IN, 
 BT_GATT_CHRC_WRITE_WITHOUT_RESP, 
 BT_GATT_PERM_WRITE, 
 NULL, write_data_in_callback, NULL), 
 BT_GATT_CHARACTERISTIC(BT_UUID_MOBILE_APP_GENERIC_UTILITY, 
 BT_GATT_CHRC_READ | BT_GATT_CHRC_WRITE_WITHOUT_RESP, 
 BT_GATT_PERM_READ | BT_GATT_PERM_WRITE, 
 read_generic_utility_callback, write_generic_utility_callback, NULL), 
 BT_GATT_CHARACTERISTIC(BT_UUID_MOBILE_APP_DATA_OUT_UTILITY, 
 BT_GATT_CHRC_NOTIFY, 
 BT_GATT_PERM_NONE, 
 NULL, NULL, NULL), 
 BT_GATT_CCC(data_out_utility_cfg_changed_callback, BT_GATT_PERM_READ | BT_GATT_PERM_WRITE), 
 BT_GATT_CHARACTERISTIC(BT_UUID_MOBILE_APP_DATA_IN_UTILITY, 
 BT_GATT_CHRC_WRITE_WITHOUT_RESP, 
 BT_GATT_PERM_WRITE, 
 NULL, write_data_in_utility_callback, NULL), 
 ); 
 
 BT_GATT_SERVICE_DEFINE(pairing_svc, 
 BT_GATT_PRIMARY_SERVICE(BT_UUID_PAIRING_SERVICE), 
 BT_GATT_CHARACTERISTIC(BT_UUID_PAIRING_UTILITY, 
 BT_GATT_CHRC_READ, 
 BT_GATT_PERM_READ, 
 NULL, NULL, NULL), 
 ); 
 
 Let me know if you require more information, I realize this is a unique design therefore giving you code to use on a development kit is not so simple. 
 Best regards, 
 Pam