The between two times can be confusing.
This is how I think of the different scenarios…
Trigger - when the trigger event occurs the actions are then done. So if the trigger event is your arrival home, the only time the actions will occur is when your presence goes from away to present. It doesn’t matter if you are home all night, it will not happen again until you leave and come back.
Conditional trigger - same as the trigger above except it has conditions. If your trigger is your arrival and your conditions are between 4pm and 6pm and the action is to open the garage door, the garage door will only open when you come home between 4&6 pm. If you come home at 6:16pm, the door stays closed.
A rule has no trigger event, only conditions. So the actions take place upon a rule truth change. If the rule goes from false to true, the actions for true take place. If the rule goes from true to false, the actions for false take place.
For example, your conditions are your present, the garage door is closed, and it’s between 4-6pm.
Actions for true, open garage door.
Actions for false, close garage door.
So, if you come home between 4-6 pm and the garage door is closed, the rule is true, this the garage door opens. Also, if you are at home and the garage door is closed and it becomes 4pm, the rule becomes true and the garage door opens.
So, the between two times is a condition to be true or false. It is also a restriction.
Trigger - an event must occur
Conditional trigger - an event must occur but these other criteria must be met as well.
Rule - all of the conditions must be true.
Does that make sense?
So in your scenario…
At 0450, if the lux is below 50, the light will come on. If the lux is above 50 it will not. But if the lux drops below 50 between 0450 and sunrise, it will come on.
The way I would do this is like this…
Rule - turn on light
Conditions - lux below 50, time between 0450 & sunrise - 12
Rule - lux below 50 AND time between 0450 & sunrise - 12.
Actions for true - turn on light
Actions for false - turn off light
This will have the light on between 0450 and sunrise as long as the lux is below 50.