I'm suspecting that when you set your time scale to 0, the Wait action doesn't apply since the time scale is now at 0.
You'd probably have a better luck creating some hidden sprite (let's name it "tim") and apply the Timer behavior to it.
When you set the time scale to 0, do also apply the action System: Set object time scale to tim so it is at 1 (the object tim is "not frozen").
Now start a timer that will last as long as you want.
When the timer triggers, set the timescale back to 1.
In theory, this should do the job.
If you encounter further issue, consider posting your project for further inspection.