I copy and paste a table from Writer to Impress. Then, in Impress I delete row 
2 and save. Opening the file, data from row 3 is also deleted.

To reproduce:
1. Open a new Writer document, create a table with 2 columns and more than 3 
rows. (For example, a 4x2 table)
2. Fill the table with something like A B C D in column 1, so you see data on 
each row.
3. Mark the whole table, copy.
4. Open a new Impress document, paste the table.
5. Use mouse to highlight all of row 2, right-click, delete row. (The table now 
looks like A C D.)
6. Save the document, close.
7. Open the document again. The table now looks like A D (empty row).