HSB is performed on AC6800V. However, the standby device displays that the AP is idle, which is related to insufficient power supply.
The AP6052 is a standard 802.3b power supply, which may be an AT standard power supply. However, it is irrelevant to the idle state of the standby AC. You need to check the configurations of hsb on the active and standby ACs.
The power supply issue, AP 6052DN need 802.3bt standard POE power supply.
AP6052DN need 802.3bt standard POE power supply.