Bios reflash caused loss of xmp recognition?

Well, then try at least to make a backup of the spi or the bios region, might be possible to restore it when things go wrong next time.

Download from Intel (Converged Security) Management Engine: Drivers, Firmware and Tools (2-15)
ME System Tools v8

Run Flash Programming Tool (fpt)
fpt(w(64)).exe -d spi.bin

or if this doesn’t work:
fpt(w(64)).exe -bios -d biosreg.bin

If your eager to know if you can write to the bios region with fpt try to write back the dump of the bios region you just created (recommend non windows- version - DOS bootable usb stick - for dumping and flashing/writing):
fpt.exe -bios -f biosreg.bin

But be careful, fpt writes without checking the content of the file or the area it writes to!