I can’t get more than 5 of my VEGA 56 to hash at the same time, currently running rigs with 8 x Vega 56

Celeron processor
Ubuntu mate 18.04
Amdgpupro 18.30

The miner initializes all 8 cards, all 8 cards show full activity on LEDs, but always 0 hashrate reported for 3 of them, only 5 ever have a hash rate above 0

Any ideas?