Zephyr BLE Mesh Coded Phy

I am trying to add Coded Phy to my Zephyr BLE Mesh project. I know this is not officially supported, however is possible. Running the stock BLE Mesh Zephyr sample, I keep getting the following error, on trying to start a scan:


[00:00:10.746,246] <wrn> bt_hci_core: opcode 0x2041 status 0x12
[00:00:10.754,455] <err> bt_mesh_adv: starting scan failed (err -22)

Opcode 0x2041 is SDC_HCI_OPCODE_CMD_LE_SET_EXT_SCAN_PARAMS, and is returning invalid parameters, however the parameters specified don't seem to have any effect. Do I need to add something to prj.conf to support this?

I have modified adv.c as:

adv_ext:

I have tried adjusting the scan window and interval as well as the advertising parameters, but this doesn't help. What am I missing?