So I decided to give 3.3.0 alpha a go and this is what I got when trying to import a mixamo rig exported to gltf from blender 2.8:
Uncaught exception thrown in Thread[jME3 Main,5,main]
RendererException: compile error in: ShaderSource[name=Common/MatDefs/Light/PBRLighting.frag, defines, type=Fragment, language=GLSL110]
0:192(21): error: cannot construct `mat3' from a matrix in GLSL 1.10 (GLSL 1.20 or GLSL ES 1.00 required)
0:193(16): error: no matching function for call to `inverse(mat3)'; candidates are:
I myself not know much too.
From experience I know most Linux users including me who are using open source Mesa driver not works without opengl3 core profile enabled.
The above command force the rendering to not use deprecated features of opengl. I guess they are not implemented in Mesa driver.