2018 CC layer mask problem? (image)

[WeeGecko]

Hi I have updated to CC 2018, and when images are showing blocks of varying shades of grey in the layer masks.  
I cannot fill a mask with white, and when brushing over the mask, the effect can appear to be brushing out, but return immediately after.

Has anyone else seen this, or does anyone know a cure?

I'm on OS Sierra 10:12:6

[WeeGecko]

Here is a screenshot of the layers palette...

I have tried to fill the Toning layer, and Curves 1 with white, with no success.   I have just noticed that the Curves 2 layer is showing a black block in the top right corner.

[WeeGecko]

macOS Sierra  Version 10.12.6

MacBook Pro (13-inch, 2017, Four Thunderbolt 3 Ports)

Processor  3.1 Ghz Intel Core i5

Memory     8 GB 2133 Mhz LPDDR3

Graphics    Intel Iris Plus Graphics 650 1536 MB

Photograph is with Nikon D810 opened in ACR for RAW conversion, and into photoshop CC 2018