On File:Atalanta - Vol. 2.djvu (Wikisource index), MediaWiki-DjVu fails to extract the text layer; exemplified at this page.
Properties of the file that might conceivably trigger a problem: it is moderately large (~320MB), has many pages (838 pages), and contains lots of text (~3MB). None of these are unique or extreme values for the range processed by Commons/Wikisource, but they do reside towards the high end. The sheer amount of text might be worth looking into as (iirc) it gets stored in a database field that isn't really designed to hold huge amounts of text (a field meant for metadata? The details escape me, but I seem to recall overshooting this size makes MediaWiki fall down in interesting ways, quite possibly because truncated and thus invalid XML is saved in a text field), and the total size in the DjVu is inflated by being wrapped in XML for storage (iirc and aiui; I could very well be wrong on all counts there).
The underlying DjVu file does have a text layer, and all manual checks of the file suggest that it is a perfectly normal and valid text layer. No relevant error messages are visible in the web browsers javascript console, and the problem is reproducible across browsers (Safari, Firefox, and Chrome tested), OS platforms (macOS and Windows tested), and users (including logged out), so it is unlikely to be a client or front-end issue.
Steps to Reproduce: Open https://en.wikisource.org/w/index.php?title=Page:Atalanta_-_Vol._2.djvu/18&action=edit&redlink=1 in a browser
Actual Results: No OCR text layer is preloaded into the text field
Expected Results: The OCR text layer from the DjVu should be preloaded into the text field