Please could you report bugs in v2 on the openlp-beta mailing list (details here). You are more likely to catch the attention of the relevant developers that way. We like to keep the forums reserved for v1.x issues.
But anyway, in your folder of a 100 pictures, can you check whether the extensions are upper or lower case? I've discovered a folder full of ".JPG"'s doesn't show but a folder full of ".jpg"'s does (which I consider a bug).