Maybe this issue is related to this one:
But, this time it's an Excel file. In the original file there were two identical adjacent source segments (client's mistake). Therefore I translated the first one only and left the second target segment empty. There were no tags involved.
Before exporting, I confirmed again that the second target segment was empty, but upon opening the exported file I found that CTE populated the empty target with the corresponding source text.
Is there a justifiable reason for this behavior?
The Excel filter will include the suggested change in the next update.