night color cannot save settings

[Graham]

The Night Color Control settings cannot be changed after setting a custom activation time.

Steps to recreate:
1. Install Kubuntu 20.04. Can be done in VirtualBox. Accept all default options. Reboot and log in.
2. In the system tray right click "Night Color Control" and choose "Configure Night Color..."
3. Click to select "Activate Night Color".
4. Set "Activiation time" to "Custom time".
5. Click OK
6. Open the settings again (ie repeat step 2).
7. Change "Activation time" to "Sunset to sunrise at current location". Note the "Apply" button remains greyed out. Normally it will un-grey when settings are changed.
8. Click OK
9. Open the settings again (ie repeat step 2).
10. See the settings remain at the values set in step 4.

Note in step 6 you can change any setting, the behaviour is the same. All changes will be ignored.

Workaround to get the dialog working again...
1. Edit ~/.config/kwinrc and delete the line "Mode=Times"
2. Log out and back in.
The dialog will now work again.

System Information numbers:
KDE Plasma Version: 5.18.4
KDE Frameworks Version: 5.68.0
Qt Version: 5.12.8
Kernel Version: 5.4.0-26-generic
OS Type: 64-bit

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.