You should consider using the Expire binding for something like this.
Anyway, the logs indicate that the rule is triggered every time that SchaltSteckDose_1_AnAus updates (you should really use changed for a Rule like this. So the binding and Items and rule triggering are working.
It’s really hard to tell because you didn’t How to use code fences, but it looks like the creation of the Timer is inside the if statement. That means the timer will only vbe created when SchaltSteckDose_1_AnAus changes to ON. The rule does nothing except logging that “SSD_1 status update triggered”, which we can see in the second set of logs.
So the rule is doing what you told it to. When it turns ON it sets the timer. When you turn it OFF, it just logs the change and then does nothing.