After a clean and rebuild there are error markers in Eclipse Problems view, although everything should be OK.
(based on the wiki entry from Sticky WOD error markers will not go away – WOProject / WOLips – Confluence)
1. Close Eclipse
/.metadata/.plugins/org.eclipse.core.resources/.projects/<your project name>/.markers for all affected projects.
The steps above resolved my case; steps 4. and 5. are mentioned on the wiki, but were not necessary to solve my problems:
3.2. Shut down Eclipse.
4. Run Eclipse and load the workspace.
5. Clean all affected projects.