The SuperMicro manuals only show a configuration of 4 dimms for 2 cpu minimum. I also doubt it's shorts since the memory that came with each system works fine. I was wanting to go from the 64GB to the new 128GB set.
I purchased a matched 16 set of Samsung M393B1G70QH0-CK0 8GB PC3-12800R memory off eBay. I have tried a couple different combinations of them in two SuperMicro servers. They have X9DRi-LN4F+ and X9DRi motherboards with two Xeons each.
I pulled the existing memory kits from each server...
2x Intel E5-2630L V2
64GB ECC REG
HP H220 IT Mode or LSI 9201-8i
Intel X550T2 Ethernet Converged Network Adapter
1 x 500GB Samsung SSD for OS
6 x HGST 6TB NAS
9 x Seagate IronWolf 6TB
2 x 10TB WD White label
5 x 8TB WD White label
4 x 250GB Samsung SSD...
It doesn't matter if you do tiering or not, parity requires you to add enough disks to cover the number of columns specified.
Think of it as a row of bricks. If you have 3 columns, that means that 3 bricks are lined up in a row. When you expand, you are adding a new row and needs the same...
I've had a lot of issues with Windows 2019 and Windows 10 machines past the initial release build. I found that disabling Large Send Offload, Receive Side Scaling and Recv Segment Coalescing on the adapters resolved the issue. Might be worth digging into and seeing if that helps.