Hi sebfortier,
as far as I can tell, this is not a bug, but is related to the way the sensor transmits its state and the way system logically connects the conditions. The sensor only transmits at the moment a change occurs and the routine reacts to the change generating action but it will not react when there is a state already existing at the moment of sunset.
So if the critical temperature is already reached at sunset, nothing will happen. Just try to define another setting in addition (!) that does the same, but for a temperature of more than 28 degrees and slightly less than the temperature was the moment when you experienced that your setting seemed not to work.
The workaround for your problem may be different depending on your hardware.
I use a “Phoscon” gateway and “Xiaomi” multisensor, a combination that allows to define a couple of rules even for the same purpose. They are not disturbing each other, but you should be aware not to create al logical contradiction when defining a couple of rules.
I hope this may help with your problem
I am using a similar setting not with a switch and ventilator, but with some IKEA motor blinds to prevent my apartment from overheating on warm days. The trigger is 23 degrees and the precondition is that it may only work when the windows are closed to prevent jam and maybe damage of the blinds at the moment somebody has opened the windows or I myself maybe had forgotten to close them before I leave my apartment.
Thanks to Thomas of HUE Essentails, it all works perfect now.
Try it out and please let me know if it works or not.
Good luck!
Peter