Adam,
You should state the version of Studio you are using, and also if it is a Local or Remote configuration. A remote configuration could explain why the build succeeds but the code editor fails, as the build will be executed on your remote server, whilst the real time syntax check for the code editor occurs on your local PC.
Is there something I should be checking within studio to confirm the paths are correct?
If you right-click on a node in the projects view, there is an option Display Environment.
import fgl modname will always give me an error in the editor, saying that the module could not be found. However the project will build and run without issue.
Are your imported 4gl's included in your 4pw?
Do they have Exclude from Link set?
If included beneath a library node, is that library linked in the external dependencies to your application?
Have you taken Target Directory into account?
Are all the directories listed in FGLLDPATH beneath a mount point.
Reuben