Impossible to say without a logfile. Unusual, though. Check for errors on the Kodi client (in kodi.log), maybe it's got some sort of problem writing to the local SQLite db or filesystem.
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.