2.80 - use Eevee and Cycles together for motion blur issue I have one question about one problem in my experiment with motion blur in Eevee. I know that in this time is not supported and maybe will be supported in future official release as another primary function, but I want to try some experiment with Vector pass from Cycles. 

I would like to try to make render of car with animation of fast rotating back wheels. I make two scenes (duplicate, not linked).

I join this two scenes with separate Layers setups and render engines together in compositor. The same node tree is in the both scenes.



It works pretty well (picture), but It has a problem. It works only if I start rendering manualy by render button on scenes nodes, but it don´t work if I push F12 or Ctrl+F12. It rendered all scenes only in one renderer in actual scene. It do not switch them.

Please help me find out a issue, where is a problem. Thanks a lot :).  

Note: For this test I use model from Blender Corvette modelling tutorial from CG Masters
I was able to get this set up by creating a separate scene that composites the Eevee and Cycles scenes together - I have both of those set up with the default composting node setup, but I'm not sure it's required. This allows it to work with all frames, or individual ones if you render from the composited scene.

If it's a sequence, that composited scene clip can then be placed on the timeline in the VSE (in a master VSE scene), but it doesn't have any preview functionality unfortunately, so I set up two tracks - one that contains the original unblurred Eevee clip, so I can edit/render things quickly with the solid shading, and the other has the composited one. I just enable/disable the tracks before exporting. I wish there was a workflow in the compositor for branching off when wireframe/solid is requested, but I haven't seen anything do that yet.

Thanks for detailing your node setup here - it was really useful!