I have just updated my bios from 1802 to 1903 and I cannot use XMP profiles as machine then fails to post and goes into safe mode. If I use the base BIOS it works and if I leave on auto and change the clock speed to that of my memory it works. Not sure what further things I could do to solve the issue other than rollback the BIOS. Up to this BIOS update not issues with using XMP.
Update: Found solution as the timings on each pair of ram was slightly different. Took them both out and then put in the one with the slightlyu lower (by 1 timings). XMP then worked. Then put in other two sticks of RAM. No problems sionce.
I had this issue on 1902 as well, and had to rollback to the beta 1901 version (the first to enable resizable bar on this board) to get my computer to post at all with XMP profiles. So I'd suggest finding that version if possible if you value XMP. It is unfortunately no longer hosted on the official downloads page from what I can tell.