Missing media file on SOME episodes

Hi, I created a few test episodes for my new podcast. But it seems that the Web Player can only play the first(?) episode.

Here are the links:

In wordpress I can see a valid file in the episodes and even the duration gets verified correctly. So the paths and file names should be correct, right?

I deactivated all other wordpress plugins. I reinstalled the podlove plugin, but it is always the same - I can play the first episode in the player and for the other episodes I get the error “Missing Media File”.

The log doesn’t show any errors, as well.
Do I miss something?

Thanks for your help!