I am not installed AMDGPU PRO drivers. I have Radeon RX 560 4Gb.
Unfortunately I have no opportunity right now to test on the free drivers. Usually from the used code it should work on them but I do not know the memory allocation rules on this drivers. Clinfo should never the less work with the free AMD drivers as well, so if you could run it and send me the output in a private message that may help me a lot fixing this

Working with my RX560 4GB 16CU and R9 290 4gb
R9 290 undervolted and underclocked @ 21.5 Sol / 115W
RX 560 undervolted and underclocked @ 8-11 Sol / 45W

Thx for reporting

I am still amazed how well the R9 290 does - I mean ... this autumn its 5 years since release and still they are close to 580 series. Who bought such a card back then did get a lot of value for bugs ^^