I am on release 21.2.2 / Adobe Camera Raw 12.4 on Windows 10 1909
I am processing a Nikon NEF file from a D7500. When using the Radial Filter the overlay appears as a box when Mask Options are active. See the attached file.
Sorry to hear about the box that appears when you use the radial filter. Could you please try turning off the graphics processor by going into Photoshop's Prefereces > File handling > Camera Raw Preferences > Performance, then relaunch Photoshop and let us know if it helps?
I have tried turning the graphics processor usage on and off. It did correct the issue when the processor was off. I've updated the drivers for the graphics card and the problem seems to have gone away. Thank you for your reply and suggestion