Based on the protocol trace taken with software from Granite River Labs, the Anker charger supports 15 watts (5 volts @ 3 amps), 27 watts (9 volts @ 3 amps), and 45 watts (15 volts @ 3 amps) power profiles. However, when you look deeper, the Anker charger is issuing source capabilities that advertise different PDO's- the first source capability advertises 3 PDO's (5, 9, 15 V @ 3 A) while the second source capability advertises 4 PDO's (5, 9, 15 V @ 3A and 20 V @ 2.25). Issuing source capabilities that advertise different PDO's violates USB Power Delivery Compliance.
In this previous review, we learned that the LG G5 can support 15 watts (5 volts @ 3 amps) or 18 watts (9 volts @ 2 amps) power charging profiles so ideally the LG G5 would charge from the Anker charger at 18 watts (9 volts @ 2 amps).
From the protocol trace below, the LG G5 does request 9 volts @ 2 amps.
However, we observe that the Anker charger is sending a HardReset message since the LG G5 does not send the REQUEST message for the Source Capabilities message sent by the Anker charger. For some reason, the Anker charger is sending the Source Capabilities message again even after a successful PD contract is closed, and there is therefore a continual series of hard resets ...
... with current staying at 0 amps...
... which you can also see over long time periods.
The result is that the LG G5 doesn't charge at all from the Anker PowerPort+ 5 USB-C with USB Power Delivery and the 'Battery & power savings screen' on the G5 shows the battery discharging as if it wasn't connected to the charger at all.
Perhaps this is due to LG G5 unable to handle multiple PDO's but more investigation and analysis is needed to see what's going wrong.