Hello,
Click on the Channel that the Podcast resides in, click on the "Repeat to fit" checkbox.
You should always make the timeline long enough for the Podcast to download as Podcasts are usually large in size. If for example you make the timeline lets say, 1 minute, it will not be enough for the Podcast to cache.
However this is not your case since you are saying it is playing fine the 1st time, so go ahead and set the checkbox for repeat to fit.
Regards,
Sean - MediaSignage.com