I’m having the same problem with my site.
Running WordPress 4.1.1 with Newspaper Child theme, RSS Multi Importer Version 3.13 and RSS Filter Version 1.0.
The feed database hasn’t updated in the last 4 weeks and no new RSS feed posts are appearing on my site:
https://www.doclens.com/firehose/
I suspect that the number of posts has caused something in the Multi Importer to choke. I was also showing the posts via a widget on my homepage, but it was slowing down the load times for the page. It got to the point where I just disabled the widget.
I have about 85 RSS feeds in Multi Importer and I use Category Word Filters. In total, since my site went live 4 months ago, I have posted about 1,800 posts using the Multi Importer plugin.
I really like the functionality of Multi Importer and want it back on my site. Does anyone have any ideas?
Thanks,
Steve