Have you tried mounting it on your PC from a command line? gparted also showed the partition as unknown (after formatting it as f2fs), but mounting it at the command line worked fine.
Texture Cache Maintenance Utility: Preload your texture cache for optimal UI performance. Remotely manage media libraries. Purge unused artwork to free up space. Find missing media. Configurable QA check to highlight metadata issues. Aid in diagnosis of library and cache related problems.