@Kev Thompson occasionally there are issues of it needing to clean and rebuild the project for configuration changes, structure, gradle updates, and any resource files to be included in your new builds. It gets frustrating at times, but it seems to be a part of the development process and I would assume yours was a similar situations.
After awhile, when things are just strange or unexpected and you've worked through the usual suspects, I just invalidate caches, clean, and rebuild and after once or twice everything magically works again. Good luck!