When adding images to an iCollage project it is common to use its iPhoto integration and directly load images through the image selector sidebar. This sidebar is opened by clicking the Image icon in the bottom toolbar and it pops out a bar with a list of albums at the top and the images at the bottom. In theory this is would be a great system, but there's a problem - when you have a lot of photos in an album (which will happen a lot for the average user) the pane that lists the image thumbnails is sized incorrectly so you don't see the images at the bottom.
(click to view the full-size version with annotations)
Update: After submitting this bug report to Wondershare and explaining to them several times that the problem had nothing to do with resizing the images, they finally accepted there was a bug and said they would pass it to the developers to resolve. Am not holding my breath.