PSA to Batch 2
While the sample size is small (three reports), RAM modules rated for 5200 MT/s do not appear to work at this time.
Suggestion
If you purchased 5200 MT/s and can still return it, I would recommend you do that.
If your return window has passed, you may still be able to return your kit if you accept a restocking fee (Amazon taxed me 20%). Of course, you can always try your luck on the used market; however, without a way to verify functionality, you may be forced to accept a reduced price.
Regardless, if you need a working machine the day it arrives, I would recommend you order a kit rated for 5600 MT/s.
You may also check latest BIOS and RAM compatibility pages to see if 5200 MT/s support is listed. Perhaps FW will have patched support by the time you are charged, but you should be mindful of any BIOS release dates to make sure there has been at least 1-2 weeks preceding your charge date (otherwise your mainboard may have been sent to fulfillment prior to the availability of the updated BIOS).
Thread for AMD RAM issues:
Latest BIOS:
List of officially compatible RAM modules: