Thumbnailing on large Multi-Page TIFF files workes fine, but there is an issue with files where each page has a different size. See example. The first page is 8.973 × 6.724 px, the second 160 x 120 px. The thumbnailer seems to use the first page's size for the second page, too. I think, this is not very important, but there may exist files where it is disturbing.

You don't need a description page because it is only a new version of an existing file, which is corrupt. So the description remains unchanged:
https://commons.wikimedia.org/wiki/File:Fairview_Cemetery_Plot_Plan_-_Fairview_Cemetery,_700_Yale_Boulevard_Southeast,_Albuquerque,_Bernalillo_County,_NM_HALS_NM-6_(sheet_1_of_3).tif

Yes, it is only for 1 file. If someone can do a server-side import here is the link to the file: