The new haze value (from WET file in UserData\player\Settings\) since 1121 has a problem to keep the value updated according to in-game setting or track default value. Details: Assume a track already has its own wet file (with customized haze value) inside MAS. If this track already has an old WET file (created before) inside UserData\player\Settings\Trackname, any weather setting selected in-game will not update this old haze value. Selecting default or none-scripted weather will enable correct haze value (read from track's own wet file), however this correct haze value is not written into WET file that located under UserData\player\Settings\Trackname. And when selecting "Scripted" weather, the old incorrect haze is loaded, and causing visual issue to the track (such as white horizon).
Only way to fix this would be to not allow per weather file customization of the value and move the settings into the GDB file. Alternatively, when you update the track, if you rename your gdb files (add an extra character at the end etc), you'll ensure that they all get the default settings.