The video above addresses an odd grey screen playback problem with Maya 2018. You open up your shot, press play, and the screen goes grey - i.e. you can't seen anything. Scrub through the timeline and the same thing happens. It's like putting on a pair of blackout shades - you can't get any work done. The only solution I have found is to open up the same shot in Maya 2017, and, under the Renderer menu in the Viewport, select Legacy Default Viewport (an option which has been disabled for Maya 2018).
Fortunately, thanks to YouTube channel subscriber Diego Gomez, there is a solution to the Maya 2018 problem, which will allow you to continue to work in Maya 2018.
According to Diego:
"You can fix the problem in Maya 2018 and enable the Legacy Renderer by using the following method:
- Go to Documents/Maya/2018/Maya.env [this document looks like a Maya file but has a file size of just 1kb]
- Open Maya.env with a text editor, such as notepad - or whatever
- type this into the document: MAYA_ENABLE_LEGACY_VIEWPORT=1 and Press Enter
- File/save Maya.env
- Restart Maya 2018 and go to Renderer in the Viewport. The Legacy Default Viewport should be there."
Many thanks to Diego for providing this super helpful solution. I have tested it out and it works great - I now have the Legacy Default Viewport in Maya 2018.