Hello,
I have recently bought an Anker Power Core Speed 20000 PD powerbank to charge my iPad Pro and other devices. But it wont charge itself with anything and any cable I have. I managed to charge it with my iPad charger but it was a very long journey. Yesterday I bought an Anker PowerPort Speed 5 wall charger… Today I wanted to give it a try and left my Power Core powerbank to charge via PD usb-C port over night. At start it had 75% capacity (3rd led was blinking)… and after 6 hours it didn’t charge - 3rd led still blinks and no progress at all. I’m using fast charge cable USB-A (connected to Anker wall charger blue usb port) to USB-C plugged into Power Core USB-C PD port.
Wall charger is ok, because it can charge my devices with fast charge. Also I once managed to recharge my powerbank and it can charge my ipad and other devices with no problem.