BlueNRG-MS v7.2c Mode4 simultaneous Scan & Advertise example?

I have achieved scanning or advertising as well as a connection as a slave to 1 master and simultaneously a master of 2 slaves.

Now I need simultaneous scan & advertise (whether or not in connection as a slave or master), but cannot achieve it.

Would someone please point me to an example which achieves this or show some code snippets that worked for them?

I am following guidelines of en.DM00141271 BlueNRG Prog Man Rev 6 Dec 2016, Chapter 4: BlueNRG multiple connections timing strategy

Specifically wrt advice 4:

Every time you start Advertising:

b) If not Direct Advertising, choose Advertising_Interval_Min = Advertising_Interval_Max such that (Advertising_Interval_Min + 5ms) is an integer multiple of the shortest allocated connection interval

The error I am getting is 0x85: BLE_STATUS_INTERVAL_TOO_LARGE

Order of work:

0. initialize Mode4:

uint8_t DataMode = 4;

aci_hal_write_config_data(CONFIG_DATA_MODE_OFFSET, CONFIG_DATA_MODE_LEN, &DataMode));

and of course dual gap role

uint8_t GapRole = GAP_PERIPHERAL_ROLE_IDB05A1 | GAP_CENTRAL_ROLE_IDB05A1;

aci_gap_init_IDB05A1(GapRole, 1, strlen(DeviceName), &gapRoleHdl, &devNameHdl, &devAppearHdl));

1. start scanning forever:

aci_gap_start_selective_conn_establish_proc(ACTIVE_SCAN, 96, 16, PUBLIC_ADDR, true, 2, whitelist);

(so 60-msec scan interval, 10-msec scan window)

2. get advertisement from one of the two slaves in the whitelist and connect:

 aci_gap_create_connection(96, 16, AddrType, Addr, PUBLIC_ADDR, 48, 48, 2, 72, 16, 16);   

(so same scan parameters as above and 60-msec conn interval, 10-msec conn length)

3. attempt to start advertising (while previously started scan continues looking for second slave in the whitelist):

aci_gap_set_discoverable(ADV_IND, 44, 44, PUBLIC_ADDR, NO_WHITE_LIST_USE, 0, NULL, 0, NULL, 0, 0)))

(so 55-msec advertising interval, obeying advice to be even interval of (60-msec - 5-msec)

Return value of above call is always error 0x85.