Merged cells become empty cells after saving as CSV

A cell merged across three rows uses rowspan. CSV has no concept of rowspan, so the export writes the value once and leaves the following rows with one fewer cell - not an empty cell, a missing one. Every column after it shifts left.

How to fix it

1. Select the whole sheet and unmerge all cells.
2. Fill the value down so every row carries it explicitly.
3. Verify the column count is identical on every row before saving.
4. Save as CSV and open it in a text editor to confirm no row is shorter.

How to avoid it next time

Never merge cells in a sheet that will become a CSV. Use repeated values instead.