Operating system: Linux-5.3.5-arch1-1-ARCH-x86_64-with-arch 64 Bits
Graphics card: Mesa DRI Intel(R) HD Graphics 620 (Kaby Lake GT2) Intel Open Source Technology Center 4.5 (Core Profile) Mesa 19.2.0
Broken: version: 2.80 (sub 75), branch: master, commit date: 2019-07-29 14:47, hash: rBf6cb5f54494e
Short description of error
When exporting an object and material to an FBX file, the Emission socket of the Principled BSDF seems to be ignored, when the other sockets are respected.
Exact steps for others to reproduce the error
Open a new blend file. Create a new material for the default cube.
Plug Image Textures into the Base Color, Roughness and Emission sockets of the Principled BSDF node.
Export the object to an fbx file.
(Optionally) delete the object.
Re-import the fbx file.
Examine the material of the imported object. The Image Textures for Base Color and Roughness are preserved. The Image Texture for Emission has been discarded.