Z axis not homing

I know this is similar to other posts on the same topic but sufficiently dissimilar for me to start again.
I have a 3018 CNC with a Woodpecker ver 3.4 controller board. I have fitted stop switches and enabled them. They work correctly when I run any axis into them. However when I try to home the machine, the Z moves up and hits end stop and ignoring the switch drives forever on, or it would if I didn’t switch it off.
I have: $21=1 $22=1 $23=0 $27=3. It happens when using grbl Candle or Easel.
Any suggestions?

Can you try with $21 = 0?

Before you home, can you get a response after sending a ‘?’ through the monitor?

The X and Z limit switch input pins are reverse marked (swapped) on the 3.4 Woodpecker board.

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You saved me by this comment. I was losing my mind. Thanks!

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