What can cause an zf7341 AP to use more than 80% CPU without any logged in user?

[cesar_murilo]

APN01_CPU is a Zabbix item that monitors CPU utilization by the AP. APN01 refers to a Ruckus AP model ZF7341.

On 07/21/2019, with no device connected, the item trigger was triggered after detecting that more than 80% of the CPU was being used.

What may have led to this high utilization?