Hello Profile - adaughe2 - Home Assistant Community,
So while it is possible to wait long periods of time in a wait or delay, it is generally not recommended. This is because HA restarts and many other possible things can happen which interrupt this 'wait’ and then it hangs as you describe.
The suggested method is have a trigger or an automation for turning it on, and another trigger or another automation for turning it off.
Your trigger happens, then waits 12 hours, so id HA reboots or there is some kind of interruption, the trigger resets.
You may want to look at a time pattern for these, they work differently…