controller: assertion in ble_ll_adv_send_conn_comp_ev

[piotrnarajowski]

Failed assertion occurs in ble_ll_adv_send_conn_comp_ev() while testing blestress app - testcase num 11.

Unfortunately, for some reason this isn't reproducing when running only specific test case. To reproduce this issue, you'll have to run all tests. You'll need two nRF52 boards. Use blestress README file to setup blestress app correctly or create targets as shown in the picutre below.

[piotrnarajowski]

FYI @andrzej-kaczmarek