evnchnIf so many devices can quick charge while Asus fast charge, suspect faulty Quick Charge handshake. Please try and see if you can transfer data to your computer using the cable you used for quick charging other phones. I suspect broken data pins...
I don't know where the ASUS charger is, maybe at work. I have a Lenovo SC-42 charger at home. Test results same asus slow charge a Xiaomi Mi5, Mi8, Redmi Note 7 quick charge. My tests prove that ASUS has problem with QC.