On a headless Ubuntu 18.04 server (updated to latest patch) using amdgpu-pro-18.20-606296 (had to hack it a bit by symlinking libamdoclsc64.so to libamdocl64.so and fixing some permissions - strace is a wonderful tool) using two stock MSI Vega 56's, it's working. Mostly.

I get:
Average speed (60s): 21.2 sol/s | 19.9 sol/s Total: 41.1 sol/s

Although one of the 56's locked up after about an hour or so and zombied the process. Had to hard reboot the system:
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Average speed (5s): 22.0 sol/s | 21.4 sol/s Total: 43.4 sol/s
New job received:
Submitting share
Share accepted
Average speed (5s): 18.2 sol/s | 19.2 sol/s Total: 37.4 sol/s
New job received:
Average speed (5s): 4.6 sol/s | 7.4 sol/s Total: 12.0 sol/s
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Average speed (60s): 17.2 sol/s | 18.6 sol/s Total: 35.9 sol/s
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Average speed (5s): 0.0 sol/s | 0.0 sol/s Total: 0.0 sol/s
Average speed (5s): 0.0 sol/s | 0.0 sol/s Total: 0.0 sol/s
Error: lolMiner detected that device 0 is stucked
Shutting down lolMiner
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