I am pointing a GetPivotData formula to a cell to obtain one of its Field Names, but it gives me a Ref error. However if I press F9 to turn that same cell reference into text wrapped with speech marks it then works fine. I don't understand why!

The formula is looking at several other cells to get additional Field names and they all work, it is just this one cell. Unfortunately I can't just F9 it as I need to be able to drag the formula down over many rows. [I have tested and the same problem persists on other rows BTW, the cell reference won't work but F9 magically fixes it!]