When you choose ‘current’ for the widget it should just show exactly what’s in the current page query.
This could be a MapPress bug, but more often the problem is that the theme or another plugin is modifying the query.
There are two things to try:
1. Check for conflicts – switch to the ‘twenty twelve’ theme and deactivate your other plugins. Do you see the same result?
2. Output the query – add this to the sidebar template file to print the current query:
<?php global $wp_query; print_r($wp_query->posts); ?>
If this issue persists after trying the above, please feel free to send a login and I’ll take a look on your site.