zephyr: Bluetooth ASSERTION FAIL [evdone] Zephyr v2.6.0

Describe the bug While developing with Zephyr v2.6.0 c9fd7a6099c4fad73014aaf0ce364996afbba9e6 our app raised this Bluetooth assert: ASSERTION FAIL [evdone] @ .../zephyr/subsys/bluetooth/controller/ll_sw/nordic/lll/lll.c:353

With a limited amount of testing I’ve experienced this twice.

To Reproduce Setup a project the passive Bluetooth scanning with a 60ms scanning interval and 60ms window with and the filter duplicates disable and set up the project to allow up to 4 connected BLE devices and up to 4 bonds.

prj.conf.txt

#define BT_LE_SCAN_PASSIVE_ALLOW_DUPLICATES BT_LE_SCAN_PARAM(BT_HCI_LE_SCAN_PASSIVE, \
					    BT_HCI_LE_SCAN_FILTER_DUP_DISABLE, \
					    BT_GAP_SCAN_FAST_INTERVAL, \
					    BT_GAP_SCAN_FAST_INTERVAL)

int scan_init(void)
{
	int rc;

	rc = bt_le_scan_start(BT_LE_SCAN_PASSIVE_ALLOW_DUPLICATES, scan_device_found);
	if (rc) {
		LOG_ERR("Scanning failed to start (rc %d)", rc);
	}
	else {
		LOG_INF("Scanning Started");
	}

	return rc;
}

Expected behavior No asserts happen.

Impact Annoyance

Logs and console output @ .../zephyr/subsys/bluetooth/controller/ll_sw/nordic/lll/lll.c:353

Environment (please complete the following information):

• OS: Windows
• Toolchain C compiler identification is GNU 7.3.1
• Commit SHA c9fd7a6099c4fad73014aaf0ce364996afbba9e6

Additional context Small discussion with @cvinayak on Slack