Will give that a go tonight and see how i get on, though it does seem strange, and very coincidental that there's a lot of MSI + 3200mhz+ issues out there highlighting similar to me. Though that doesn't really explain why i can't make the timings any better even at 3200mhz. Read one guy was happily doing 3800mhz+ with a 3000 series in his board, plopped a 5000 in and couldn't break 3200mhz. Of course that could still be an IMC issue but i have strong suspicions of a bios issue.
I've tested some Corsair Vengeance LPX and RGB Pro, both 3600MHz kits and they worked on my 3600 on an Asus Tuf Gaming X570 Plus. In fact I managed to clock them to 4000MHz with looser timings which means the 5600X you have should easily handle 3600MHz ram if a Ryzen 3600 can do it. It must be a bios issue imo since I did get unstability when I flashed the latest beta bios so suspect MSI boards will have similar issues.