I’ve imported it in sketchup and I’d like to be able to use “union” and “substract” tool with it but it keeps telling me that it’s not a solid or locked.
Think is, Solid inspector tells me everything is fine. The is only one component/group in the file. Outliner tray shows only one component.
If there is only one component in your model, what are you going to union or subtract with it? You need more than one solid to use any of the Solid tools.