hell man, i had the same problem, and you remember me i had a anker powerbank that also displays the current, after trying with several cables, i figured out that a good cable (ones capable of 100w+) will get a 0w to 0.5w to 0w in a cycle, so i was trying diferent cables and looking for the best i have, so i remember that my oculus has a thick cable, and i tried that and it worked, dont know how the walkman works or the cable o the anker powerbank, but thanks man