This is more meant as an information or warning as I do not expect a fix for this issue.
The ANKER Nano II 65W I use to charge my Pixel and notebook without an issue simply won’t charge the FP5. The battery icon changes to the charge symbol for a second and then turns back. Other cable doesn’t change a thing. And a really spooky thing happens as well: A ghost-like wave moves over the display from bottom to top when plugging in the charger 
thats the normal android start to charge animation XD
but yeah, its really strange that its not working with your charger ^^v
Ah thanks, I did not notice that animation on any other charger so far 