Did you check for RAM and motherboard compatibility in
the memory QVL for the motherboard?
Your motherboard supports up to 4000MHz RAM frequency (OC), if the RAM and motherboard are compatible.
The 3200MHz XMP profile advertised by G.Skill is only a guarantee that the RAM are capable of operating at that frequency. The XMP frequency is only guranteed under optimal conditions - some configurations may not be able to achieve the 3200MHz stable.
The XMP frequency is an overclock, and overclocks can't always be quaranteed, it also depends on the CPU IMC and the motherboard.
The memory controller in the CPU might not be able to support that frequency, which could be what's holding you back in this case.
Sometimes adding a little more DRAM voltage to the RAM, can help achieving the XMP frequency.
Try bumping your DRAM voltage to 1.40v and see if that helps - it is worth a try, but it doesn't always help
If you have the options in BIOS to manually adjust IO and SA voltage, that can somtimes also increase memory stability, but usually that is not neccessary to change, unless you are trying to run very high XMP frequency settings. 3200MHz is fairly common, and usually don't require a lot of manual adjustments to run well.
EDIT :
Do you have the option to choose between two different XMP profiles in BIOS? (XMP I and XMP II)
If you do, XMP II are the settings specified by G.Skill
XMP I are XMP settings tweaked by ASUS.
If you have the option, try both XMP profiles, and see if one of them is possibly stable at 3200MHz