Color/materials suddenly goes darker?

[unmanchun]

I got the same problem and just solved.
Seems have to turn the color mode in Sketchup to align with the graphic card of the device.

Solution:
Go to System Preferences > Open GL> Capabilities
Then change (try) the color mode.

After changing to the correct one, the viewing color on sketchup screen will align with the color of the device system and hence the exported image.

UN