Lightroom CC desktop Linear and Radial Gradient not working

I’ve been following the Lightroom CC tutorials but the Gradient tools don’t respond as shown in the tutorial instructions.

Linear Gradient lines appear ok, but none of the sliders change anything at all.

Neither the Linear or Radial Gradient works in Lightroom CC.

Both work in Lightroom Classic, so I don’t think I’m doing anything wrong in Lightroom CC.

I am wondering if deleting Lightroom CC and re-downloading from Adobe would help,

Or is there some known fix to my problem?