I have the same problem I have contacted AMD support. Hope to get a helpful answer.
What's your power supply? Also, they are docked in PCIE x16 225/ 300 Watt ports? Some PCIE slots only provide about 75 Watts. It really sounds like a power issue. Each card draws north of 250 Watts under load (approaching 300 Watts). I would recommend at least a 800-850 Watt power supply. That should leave room for something like a 140-160 Watt Xeon, or i7 Processor.
There are Youtube videos of people benchmarking and running Quad Crossfire Pro Duo 32GB models, but I don't know that they are workstations.
Any help, I have 3 Pro Duo Polaris running with allot of instability in windows 10, cannot update to windows 10 1803