FCPx Timeline has turned Greyscale

All working fine until FCPx (10.3.1) crashed when relinking some files, though they seem to have relinked successfully. Upon reopening, the timeline for my project is greyscale (both shapes and video clips) and viewfinder black. Some assets are also used in another project, they load and look fine there. Blend mode is normal on everything. When I replace my main story line clip with another it also turns greyscale.

In the View finder, I am set to view ALL channels.

Can anyone shed light on why this project has gone grey, and nothing appears in the Viewfinder?

Urgent help appreciated, thanks.

Geoff