Thanks, herf, Your reply somewhat supports what I was suspecting -- that what I actually need might be more like the 'Inverse' of the Ease of Use and Accessibility filters. I will go and look at the resources that you've pointed to. Thanks,

We don't know of any updates in High Sierra that should affect this - did you add any hardware/external displays or anything like that.

Thanks - we will fix. This was only supposed to update when you pull down the menu (otherwise it can cache because it's not changing).

For reference, I've observed this issue on HollowKnight, and on MTG Arena. But I suspect that it'll apply in any game which overrides the default mouse cursor, and then resets it on close?

Usually this means you need to set your location from the f.lux preferences menu.