@Qgil-WMF and @Shirayuki - Thank you for creating this template. I am having some problems with align. Centering does not seem to work. The default seems to be left rather right. See https://www.mediawiki.org/w/index.php?title=User:PhotographerTom/Sandbox&oldid=4436436 for more details.
Topic on Template talk:Image/Flow
That template seems to be incomplete and/or incompletely copied over---the "percentage" parameter is not even used, the default on the originating site is also left not right, and the relevant css is missing from here too (hence why center doesn't work).