Apply Image with LAB equations not working correctly

[BeauRX]

As expected, and per the LAB model, the Color panel with settings (L=100, a=128, b=128) yields orange, (L=100, a=128, b=128) yields Cyan, (L=100, a=0, b=0) yields White, (L=50, a=0, b=0) yields Gray, and (L=0, a=0, b=0) yields Black.

But using Apply-Image with LAB channel equations, I was unable to create a grayscale pixel layer of the Lightness channel by setting (DL=SL, Da=0, Db=0, DA=1) and using the Bottom “color wheel” layer as source. As you can see from the “color wheel” layer the previously white background is a pure cyan (R=0, G=255, B=255) or (L=1, a=-1, b=-1). I have tried unsuccessfully with both a RGB document and LAB document, so that is not a factor. 

I tested a couple extreme values, setting the apply Image to use (L=SL, Da=-1, Db=-1, DA=1) which surprisingly produced a grayscale layer rather than the expected cyan. Similarly, apply Image with (D=SL, Da=1, Db=1, DA=1) produced a grayscale layer rather than expected orange. But to my knowledge these are both not consistent with the LAB model and in both cases the layer thumbnails were not colored consistent with the layer images, another inconsistency.

Finally these are independent of Metal [MacBook Pro (15-inch, 2016), 2.9 GHz Quad-Core Intel Core i7, 16 GB 2133 MHz LPDDR3, Radeon Pro 460 4 GB, macOS 11.2.2]

ApplyImg-LAB-err.afphoto

[IPv6]

There is clearly a bug with equations when hardware acceleration is enabled and when it is disabled //
Try to disable in in perfomance settings and all of sudden equations will start to work as they should

[BeauRX]

Thanks for the tip, but disabling GPU/metal does not seem to work for me? Settings shown below.