Hi Aleck,
I have checked my emails again and I have received two from the developers of WP e-Commerce. They are aware of the problem and they will probably fix it in WP e-Commerce 3.8.8. They have also explained to me the problem from their side and it is better to modify the podpress.php file until the new version of WP e-Commerce will be released.
podpress.php (v8.8.10.12) line 300:
old:
add_action( 'pre_get_posts', 'podPress_feed_content_filtering' );
new:
add_action( 'pre_get_posts', 'podPress_feed_content_filtering', 7 );
I was not sure about which of these ways to work-a-round the problem is the better way. But after read the mail it is clear now. Modifying their file, as I have it suggested earlier, could lead to different problems.
Because they will fix this in their plugin, I will not include this modification in podPress. (If the next podPress version will be released earlier than that you will probably need to do this modification again.)