I prepared standard TIFF files using Fiji's Stitching. Although in previous tests, those stitched large images are properly displayed in OMERO, OMERO failed to display a new series of large TIFF images. Only differences I can think of is the image size, which is bigger this time, and the fact that I run Set Scale from Java API rather than GUI. The images appear normal in Fiji. Well, perhaps ImageJ update might also be involved.
If you need, as long as it doesn't go public, I can send you an example of such TIFF files.