Gallery images are sorted and laid out based on File Name.
When importing or renaming in LightRoom, be sure your sequence # starts with (00001) - you can change this in the File Name Template Editor in LightRoom.
Your file #'s must have at least four 0's in front of the 1
Do this, and our Gallery builder will sequence your gallery correctly! :)
NOTE: There may be some slight variations in a Gallery due to dynamic image page layout (iPhone vs. iPad vs Laptop, etc.)