So, that memory kit IS validated for that motherboard, specifically, and should run at the XMP profile settings without any trouble. Either there is an incorrect setting or a faulty hardware component such as one of the memory modules.
Have you tried leaving only a single memory module installed, in the A2 slot, which is the second slot over from the CPU socket, and enabling A-XMP with only a single module installed, and then removing it and trying the other one in it's place?
If that won't work at the XMP settings even with only a single module installed, then I'd pull the CPU and check for bent pins. If it DOES run with one of the DIMMs installed, at the XMP profile, but not the other, then I'd RMA the WHOLE memory kit for replacement. If it works with each stick separately, but not together, at the XMP profile speed and there are no bent pins, then I'd begin to suspect the motherboard itself.
I'm assuming you ran the Memtest86 test with both memory modules at the default configuration, but did you run it for FOUR complete passes, or just one pass? Four complete passes is required to even get somewhat of an assurance that it's not the memory and even then, there could still be faults with the memory as Memtest86 is not always 100% accurate, especially when you are running the free version that does not have ALL of the Memtest tests included. It has only 11 of the 13 recommended tests, but even at that it is usually a very good indicator of whether there is a problem or not, it just isn't a 100% definitive answer.