[4.1.0.23][Android] Cannot switch to dark mode

REPRODUCIBILITY (% or how often): 100%
BUILD ID = OS VERSION (Settings > About product): 4.1.0.23
HARDWARE (XA2, Xperia 10…): XA2 Plus
UI LANGUAGE: German
REGRESSION: (compared to previous public release: Yes, No, ?): Yes

DESCRIPTION:

I cannot activate dark mode, nothing happens toggling the switch for that in android settings. It is back to disabled if you restart the settings app. This was working in 4.0

PRECONDITIONS:

STEPS TO REPRODUCE:

  1. Open android settings (for example using aliendalvik control)
  2. Go to “display”
  3. Try setting dark mode to on

EXPECTED RESULT:

Android applications are using dark mode.

ACTUAL RESULT:

Android applications are still white.

ADDITIONAL INFORMATION:

(Please ALWAYS attach relevant data such as logs, screenshots, etc…)

Strange. On 4.0, mine(XA2) always has failed to activate dark mode, while it got activated from the 1st try now on 4.1