Steps to reproduce behaviour:

• 1. Go to https://en.wikipedia.org/w/index.php?oldid=939185856#Maplink
• 2. Click on the link (created by the wikibase #statements parser function) that reads "40°41′21″N 74°2′40″W"
• 3. Click on "External maps"
• 4.
• - 4a. Click on "OpenStreetMap".
• - 4b. Alternatively, click on "View more", then click on "ACME Mapper".

Observed behaviour: In my browser window, I see a nearly empty webpage (only some controls, no map).
Expected behaviour: In my browser window, I would like to see a map (with the corresponding controls).

However, if I (in step 4) click on "GeoHack", and then, from the "GeoHack" webpage, I click on "OpenStreetMap">"Map" or on "ACME Mapper">"Map", I do see the map. This shows that the problem apparently does not lie within OpenStreetMap or ACME Mapper, but with Maplink (via Wikidata). Maplink (via Wikidata) apparently provides some external map links that are broken (including those for OpenStreetMap and ACME Mapper), while the links provided by GeoHack (to OpenStreetMap and ACME Mapper) are apparently fine.

Possible cause:

A missing zoom attribute might be a cause of the problem. This problem was already reported as part of the description of T225350. T225350 was closed as resolved; hovever, the problem described above is indeed not yet resolved. Regarding the possibly missing zoom attribute, see in particular the comments at T225350#5244713 and T225350#5851510, and see T227402.