If the issue appears again try using
Window > Model Info > Statistics > Fix Problems [and also '
Purge Unused'].
See if it reports problems -
Sketchup does sometimes get its data-base knickers in a twist.
This could explain the 'missing' face materials - the Exporter will always export/use the face's material IF it's returned when the data-base is queried. Faces that are inside a group that don't have a material, but the group does, can look OK as they display the group's material in
Sketchup and they should export OK too - however, it is best to 'color' the faces direct for rendering, and essential if UV-mapping is intended on any textures.
These two code snippets pasted into the
Ruby Console will return the name of a selected face's front and back materials
Sketchup.active_model.selection[0].material.name
Sketchup.active_model.selection[0].back_material.nameIf the face has no material a 'Nil' error is displayed.
There's are two options under
Window > Preferences > General that should be 'checked'
Automatically check models for problemsand
Automatically fix problems when they are foundthese will ensure you model is kept as 'correct' as possible without your intervention...
I've attached a
TroubleshootingStyle.zip file - extract the '.
style' file that's in it and put it into your '
Styles' folder.
It's useful to show what might be wrong with a model - non-axial edges, hidden lines, unexpectedly reversed faces etc.
I have it as a '
Style' in my default template and set under a '
Troubleshooting' scene-tab [one that doesn't change camera but adjusts other settings] - that way I can quickly toggle between scene tabs [keeping the view unchanged] and see what might be wrong with my modeling - like reversed faces that aren't obvious in a 'textured' view mode...