Photoshop Colour PIcker Selecting Text Colour From A Separate Layer

Hello,

I'm running Photoshop CC 24.2 on a Mac Pro (Late 2013), on MacOS Monterey Version 12.6.3.

I'm trying to change the colour of my text and want to match it to a colour in the layer below using the colour picker.  However the colour picker is only allowing me to select a colour in the same layer (i.e. the text layer which is defaulted to black).  It won't select a colour from anything else.  I'm sure I used to be able to do this!