When the RSS feed is generated the hashtags are processed just like on the frontend of your website. But after successful generation of the links they are removed because WordPress removes any HTML tags from RSS content…
I’ll think about adding a feature to keep the links generated by hashtagger in RSS. I’m not sure if it makes sense because normally you don’t want to have links inside a feed.
For a quick solution you can add the following line to the functions.php of your Theme:
add_filter( 'the_excerpt_rss', array( $hashtagger, 'process_content' ), 9999 );
This is not a good solution because the RSS content is processed twice but it should work. Also keep in mind that this will be overwritten on updating the Theme.
Please let me know if this works for you.
Regards
Peter