Another possibility: The other party accidentally deleted everything which has a strikethrough. What happens if, instead of viewing it as "Final showing markup," you view it as "Final," "Original," or "Original Showing Markup"? If the struck out text disappears completely under Final but is visible without the strikethrough under "Original," that is probably what had happened. If that is the case, you can simply reject that change to eliminate the strikethrough.
Joy,
Lynn
