Issues with grayscale

[Bvdmgg]

The first few weeks, grayscale worked perfectly. Now, sometimes it works, sometimes it doesn't. Have tried both the not-list and only-list. Once I change the settings, it works properly for half an hour or so and then goes back to showing apps I want in color in grey and the other way around.

[hamzah4]

Has the app got the correct permissions and could another app be changing the setting.