The problem, as well as my own findings are described here:
http://forum.joomla.org/index.php/topic ... #msg295581
A quick summary:
It seems that Newsflash delays publishing of content items until a certain amount of time has passed. For me this amount of time is two hours, which also happens to be my current offset from UTC. I am UTC+1 usually, and at the moment with summer time I am effectively UTC+2.
The problem seems to center around the check for the start publish time. The comparison works, it's just that for me the comparison is out by two hours!
Many people won't notice this because they'll sit there scratching their heads trying to work out why their items aren't publishing, but after a couple of hours (I'm guessing this varies by timezone) it will suddenly start working and they'll assume that they must have made a mistake somewhere.
To duplicate:
1. Create a new content item in whatever newsflash section/category you are using.
2. Go back to the frontend and see if it is displaying. If not:
3. Manually modify the start publishing date 2 days into the past and repeat step 2. If it now displays:
4. Bring the date/time forward to a point which is still in the past, but closer to actual time. repeat step 2.
5. Continue until you have found the offset from current time required to display the content.
I'd be grateful if someone could confirm this as abnormal behaviour
