Could it be that all of your post images are external, that is, not hosted in your site? (either in /data/uploads or /data/thumbs)
External images are not currently supported by NM Addons.
[edit] Well, it can be forced to display external images if you insert
before nm_custom_display...
External images are not currently supported by NM Addons.
[edit] Well, it can be forced to display external images if you insert
Code:
nm_set_option('imageexternal',1);