You can try the following, but be careful to follow instructions carefully. Using your sample file:
1. Filter the range for M
2. We are going to place the results in column F, so select cells F2 down to level with the bottom of the table. (in this case F2:F9, even though some cells are invisible).
3. With those cells still selected, on the keyboard, type the = sign, then using the left arrow cursor key on the keyboard, press it until cell C2 is selected. Do not use the mouse for anything at this stage.
4. Hold down the Ctrl key on the keyboard and press Enter on the keyboard. This will put a formula in all the selected (but only the visible) cells.


5. Clear the filter from the filtered range.
6. Select all the cells from F2:F11 as a single block (actually you need only select all cells with formulae in, but it must still be as a single block) then…
7. Copy|Paste Special, Values.
QED

I wonder whether HIV 7 has his problem solved? …