All - The 500 image limit is a bit tricky to work with ... or perhaps not as obvious as it should be. Either way we will be reviewing its functionality based on this type of feedback. Thanks!
Also, changing this value does not necessarily affect existing galleries, especially those inserted via the ATP. In most cases, you will need to re-insert the gallery that is being limited by the value (default 500) set under Gallery > Other Options > Miscellaneous.
After changing the value to a higher limit and re-inserting the gallery all should work correctly for this issue. If it does not please submit a Bug Report (http://www.nextgen-gallery.com/report-bug/ ... referencing this topic may also prove helpful) so we can have a closer look at what might be happening and try to get it sorted out on your site.
Thanks!
- Cais.