There is no technical limit in the code of the addon, but people have reported problems when they put too many images on one page (usually over 100, but depends on the power of your web server) because it takes C5 too long to generate thumbnails for all of them. Try reloading the page a few times to allow C5 to churn through the thumbnailing... or if that doesn't work try removing half of the images from the file set and reloading the page, then adding back in a few dozen at a time and reloading each time.

Hope that helps!

-Jordan