Is the "imageoverlays" option long deprecated?

Because when I tried it out in my own wiki's sandbox (and on SMW.org's Map Editor) a while before press time, not even a test image appeared over the respective default OSM/GMaps layer. Code specimen for reference:

{{#display_map:11.5,-53.5
|zoom=5
|imageoverlays=13,-52:10,-55:Example.png~Map}}

From the looks of it, I think I now remember experimenting with something similar on a Referata wiki of mine, back when that semantic host used to operate. Either that, or the Maps extension has long upgraded to the point where this feature may have been quietly retired a few years ago. (And before you ask, |image layers=Example.png is a nice thought, but only displays the target image and not the base map layer. Although, for non-Wikimedia outlets like Miraheze, this might as well prove to be for large images hosted there what Wikimedia-exclusive ZoomViewer is for WP/Commons et al.!)

If I can't find/approach a workaround in the next several days/weeks--especially while eschewing GeoJson--it'll be too soon.

Coming from a contributor who specialises in maps of geofictional realms part-time; testing on behalf of "Borderman", a Miraheze user who asked twice in the past two months on the Community noticeboard about similar support as regards Ordnance Survey material. I was about to sign up for SuperUser just for that alone, but went ahead with Plan B here.

(MW 1.39.3 (56751eb) / PHP 7.4.33 (fpm-fcgi) / SMW 4.1.1 (c5a1042) / Maps 10.0.0 (4fe56fa))

Start with the supplied #display_map example and the imageoverlays option, reproducing it under Maps 10.0.0 with MediaWiki 1.39.3, PHP 7.4.33, and SMW 4.1.1. Done means establishing whether the option is supported or deprecated, and documenting or fixing the behavior while preserving the base map without GeoJSON.