You bought this
Using a QC charger it should
You also bought this
Which is a QC charger therefore it should be 10 hours, you have the right charger for the battery, so the root cause to be eliminated.
If it is not then I'd look at a different cable, oh and don't say you used the supplied cable, it can be at fault. The thicker and shorter the cable the better.
If a different cable is no better then its either the charger or the battery at fault. Presumably you bought QC charger+battery as your device is QC. Try that charger with your cables in a QC phone and see if its recharging as fast as claimed, if so then we eliminated it back to the Powercore at fault. If it doesnt then after trying 2 cables it should be the charger's fault, use the charger which came with your device which (assuming your bought QC Powercore due to wanting QC for QC device) should be QC itself.
Hence in sequence
Eliminate cable - Try different cable - if this fixes it then was cable fault, otherwise continue
Eliminate charger (you need a QC device like a QC phone) - Connect the charger to your device, two different cables. If this fails you know it is the charger at fault. For completeness do the next steps anyway
Try your non-Anker QC charger (you got with your QC device e.g. phone) with the cable you found worked above with the Powercore. If this fails then you know the Powercore is at fault.
Once you know what Anker is at fault, then email firstname.lastname@example.org with your order details, serial numbers of the affected parts and evidence you tried to eliminate causes via different cables and chargers, and they'll set you right. It is currently about 1 to 2 working days for Anker to reply so if you put all the facts in 1 email at the start you'll get to resolution fastest.