Thanks for the tip - I don't think that is the problem after checking it, but I do appreciate the suggestion. The feed works into the DB and the items show up on the main page, but not the category or post pages.
I am not sure where the bug is, everyone says the bug is elsewhere. It seems it is an interaction between the WP Filters and RSS Agg. The only difference is the calls in query.php (WP_Query call) in line 2544. If I suppress the filters in there then it works on all pages not just the home page. As long as the filters are applied then the plugin generates the wrong query, causes an SQL error, and returns a null result. I am not sure why the plug-in needs a filter for its query, likewise, I am not sure what other filter is applied there on the other pages but not the main page.
I'm thinking that if I were to alter RSS Aggregator's code to remove all filters for the pages, categories etc using:
prior to RSS Aggregator's WordPress query, then it would work (since if I manually comment out the filter call in query.php it works on all pages). I haven't tried it yet though since it has been a lower priority.
Anyway, the SQL error when the filters are applied:
" Not unique table/alias: 'wp_postmeta' for query SELECT SQL_CALC_FOUND_ROWS wp_posts.ID FROM wp_posts INNER JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id) join wp_postmeta on wp_postmeta.post_id=wp_posts.ID "
My current "solution" has been to just not use the news on the non-main page. If I do ever figure out what the issue is exactly (or try the remove filters) I will follow up.