I've done yesterday a factory reset.
I'm afraid but i'm thinking to give back the phone and release negative feedback on Amazon.
The Umi support is the worst i've never seen and nobody say if this is a known software bug: in this case i can wait for the resolution.
But nobody is here to answer to the issue.
Hi I don't think that there is something wrong with charger plug. I would advice you to check for alien objects in USB ports.
Maybe USB cable cracked inside cause low current flow.
Please swap USB wire and test.
Phone and charger supporting quick charging up to 2.5A of course usb wire too.
Maximum current flow will be from 1% up to around 80%,then current flow will slow down to save battery.