TLDR: Take out all mem sticks, turn on computer, wait for it to not post, turn off, load 1 stick of ram, turn on and wait for post, load desired DOCP profile and go from there.

Long version: I have the same ram but with the Asus x370-pro.

Question 1) What bios do you have?

Question 2) Are you by any chance using an RGB strip connected to the mb?

So I ran into a problem this week when I was trying to do some minor bios adjustments and had coincidentally connected an rgb strip to the mb header. Prior to that time I was able to run the ram at any speed up to 2933, albeit not with pure stability. Then once I tried to reboot it would not post at all, the system would turn off and on 3x until it posted in safe mode.

I thought I messed up some setting by accident so I loaded the uefi defaults. It posted with the default memory setting but as soon as I loaded the docp profile it would not post until it went into safe mode, even down to the slowest speed of 2133 I think. So I was getting ready to hit it with a sledgehammer, but first I took out all the ram (just 2 16gb sticks) turned on the machine, turned off, and then put 1 stick in and then on again. This time it posted fine and finally I could load the memory profiles. Put in the 2nd stick and it worked fine.

So try that. Take out all sticks and clear the cmos (take out battery to be sure) while you are at it. The reason I suspect the rgb strip has something to do with it is that I have read some things about it corrupting ram something or other. And I had just out one in before the men went to crap.