I have the exact same problem!
For me, it works once in a while.
But I noticed that it works almost all the time if the car is connected to the charger, even if not charging.
I also noticed that if the last status update in the app is recent, it usually works. But if the car is left alone and not connected to a charger, then the last update in the app is the time when I locked the car, which seems to indicate that the car does not talk to the servers after a while.
One thing you can do to test if you have the same problem as I do is this:
In the morning, after you left the car alone for the night and not connected to the charger, just go to the car, open the door, close the door and leave. Make sure it locks itself again or lock it manually. This way you "woke up" the car.
Then go back inside your home and try the start the pre-conditioning from the app. Then it should work.
It works for me every time when I do this.
It also works if you unlock/lock the car from the key card from inside the house if you are close enough to the car.
All this to say that for me it looks like there is a hardware problem with the communication module which goes to some sort of deep sleep after a few hours and it is then impossible to reach the car from the Renault servers.
I am currently talking to Berg Auto about this and it looks like they agree with me after having seen the same problem on another Zoe ZE50. They are waiting for some sort of approval from Renault France to be allowed to charge the relevant part.
Let me know if my trick works for you!