As a workaround delete the offending caption, then copy and paste another, working, caption into its place.
The pasted caption should retain the numbering scheme and correctly display as 6.2.
If that doesn't work, try deleting the table and retyping it. Make sure you delete all hidden text and paragraph markers between the text and the table.
Something is causing the numbering to reset. It is often a wild goose chase to track down exactly what is causing it.