"Install overnight" option does not apply update over night
Are you sure your software did not update?

Try to check it.

Open Settings-About Phone-Software Information

Check Security Software Version and Android Security Patch Level as well.

In Security Software Version, month of installed software is mentioned.

Why software not updated overnight ?

Well, this may be due to these possible reasons:

• Your device battery was running low that time.

• You have enabled any type of battery saver.