Excel Use COUNTIF across a range of cells with formulas

[Measterbro]

I am trying to count the number of cells in a row that contain the letter "O". Every cell contains a formula. If I use this it works correctly and returns a one since D3261 has that letter:

=COUNTIF(D3261,"O")

However if I use this, I get a zero even though D3261 still has that letter:

=COUNTIF(C3261:D3261,"O")

If I remove the formulas from C3261 and D3261, and manually type the letter "O" in D3261, both formulas work correctly.