Hello @mintaras,
Okay this makes sense, post type podcasting does not mix with blog post categories. Though you can use blog post (post type of type “post”) categories with custom post types, the category feeds on WordPress will only use the posts of type “post” for the category feeds. As far as PowerPress adding podcast support in different ways, there are 4 ways and they are specific, they cannot be crossed together.
Category podcasting – Uses the post type “post” and can extend the category feed to include a special podcast only feed.
Podcast Channels – Uses the post type “post” and allows you to add multiple feeds using the same blog posts. This is useful for multiple media formats, like an audio feed and a video feed.
Post Type podcasting – uses a custom post type and allows you to add a special feed slug to that post type. Multiple feed slugs achieves the same result as podcast channels. Post type podcasting is specific to that post type.
Taxonomy podcasting – uses a custom taxonomy (taxonomies is how categories is created for post type “post”). Unlike categories that are very strict, taxonomies can be defined in many different ways, which makes it very difficult to control. For example, we cannot provide ea podcast only feed for taxonomy podcasting because it is possible you could put the same podcast episode into multiple taxonomies. Because of this, Taxonomy podcasting is the least flexible format to podcast, but in some cases, may be the only option due to a complex formatted website.
You need to pick one of these 4 methods.
Can you explain what you are trying to accomplish? I can advise what may be the best way to approach the problem?