Windows 10 machine stuck in Greyscale mode

Question

My lovely cat walked across my keyboard and now my Windows user profile is completely stuck in grey-scale mode. I have done all the typical things like disabling Color Filters, and checking Color Management. I have also checked my NVIDIA Control Panel, and all color profiles etc. are simply default.

I have also confirmed that this is not a monitor issue, as this affects all 3 of my monitors, and switching users fixes the issue.

Am I missing something here? How can I fix this?

Answer 1

After a brainwave, it was discovered that grayscale mode had been accidentally activated in f.lux by pressing Windows+End.