There is a rate limit to how fast you can publish events so the cloud does not get overloaded. The rule is one per second average with a burst of up to four allowed.
thanks for the quick reply, this makes sense now. my previous delay of 200 was way too fast and was probably maxing out the publish limit ( this explains why I could see the publish 4 times before it gave up)
I have now modified the delay to 3000 and I can now see the published output as expected.