I have this same issue, although I'm running 18.0.2.  

stupot@sabayon ~ $ glxinfo | grep OpenGL
OpenGL vendor string: X.Org
OpenGL renderer string: AMD Radeon (TM) RX 480 Graphics (POLARIS10 / DRM 3.23.0
/ 4.16.0-sabayon, LLVM 5.0.1)
OpenGL core profile version string: 4.5 (Core Profile) Mesa 18.0.2
OpenGL core profile shading language version string: 4.50
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile
OpenGL core profile extensions:
OpenGL version string: 3.0 Mesa 18.0.2
OpenGL shading language version string: 1.30
OpenGL context flags: (none)
OpenGL extensions:
OpenGL ES profile version string: OpenGL ES 3.1 Mesa 18.0.2
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.10
OpenGL ES profile extensions: