After several unsuccessful attempt to contact Lemons Dream's tech support about a potential update/fix it looks like it may be time to move to a new software.
As a short time solution, I have been using my favorite text editor (Smultron) to edit the xml file. For those who are looking for a more intuitive solution, you can download for free on the Apple app store.
Ideally, I am thinking to move to an online xml editor. An online solution would finally allow anybody in the team to publish the podcast. So far, I have to be contacted once the files are uploaded to publish as the software was hosted on my personal computer (not very practical during holidays or when traveling).
If anybody has a recommendation to do, please drop me a line or comment this article.
trashing all the Podcast Maker preference files seem to fix the situation. So far I'm still using it (now on lion) however a robust online solution probably would be better.
update 2015: it looks like That Podcast Maker by LemonzDream is dead. The website has disapeared and the developper is unreachable.
Unfortunately, it looks like the software is not compatible with Yosemite (10.10) so a new solution will need to be found.
We are going to test an online solution "Podcast Generator" to see if it could replace it. If it does, it would be great as it would be accessible to all our editors and it's also an open source software.
update 05.2015: An other update as I got a few requests about which solution we chose. In the end we went for Podbean.com for our usage it was the best service when looking at all options (including server space...)