If your Zaps don't work the way they should, how do you go about fixing them? The best thing to do is to go into the task history and follow the chain of events to see what happened. You should see a task that hit an error or filtered out for some reason. You can then view the data to see why the error occurred.
Was all the correct information submitted and in the right format? Often filters can cause issues and you need to think carefully through the logic of what data is required to make a Zap run (what if a field is empty?).
Sometimes apps get disconnected. Try reconnecting or see if it's been updated.
TIP: Run through your Zap manually through each step with a clean set of test data.