If I plug the hub into the power supply, my Samsung Galaxy S5 will charge at upwards of 1A, and my Amazon Fire HD 8 (6th generation) will charge at upwards of 0.8A. (And, the Fire HD will not complain about being attached to a low power charger.)
However, if I connect the USB hub to my Linux Desktop (Ubuntu 16.04, kernel 4.4.0-93-generic), both devices charge at only ~0.5A, as measured by an inline USB power meter.  And, the tablet complains about being connected to a low-power charger whether or not it’s attached via the power meter.
I’ve been contemplating what the problem could be, since almost everything is relatively new and unknown to me in this setup. I was curious if the linux kernel would handle power negotiation in this case, and thus could possibly be a driver issue; but I was informed by a Linux USB driver expert that the kernel does no such thing, so the problem would have to be with the hub and/or devices. Not sure what charging profile(s) my devices support, but your website says this hub supports both the Galaxy S4 and Kindle Fire 8.9,  earlier products marketed under the same model name.
 https://www.amazon.com/gp/product/B01…is the power meter I have. Not sure how accurate it is, or if it could possibly introduce any power negotiation problems (I was disappointed it didn’t have USB 3.0 pass through), but I am reasonably confident in this device at this point.