Getting "Missing proxy" despite using just Optimized media
I'm new to FCPX and have gone through some reading up on the difference between using optimized vs. proxy media for editing. As a result, I've opted to set up my editing workflow using optimised media only. I created a new event and imported the associated native files, selecting "Create optimized media." I've left "Create proxy media" unchecked. Following transcoding, all the media in the Clips window are blanked out, with "Missing proxy" stamped on each clip. I've deleted and retried, ensuring that I've not got "create proxy media" selected, but I still get this. Any advice on where I'm making a mistake?
MacBook Pro, macOS Sierra (10.12.2)