Map won’t display at specified size

Plugin is installed and activated on a development site. In the page editor is this, just to test whether or not the map would display:

<div style=”width: 1000px; height: 600px; background: #fcc;”>

[webmap id="861c955cc2bd47b68f8e4961eacb1370" width=”1000″ height=”600″ legend search home]

</div>

Both the container div and the shortcode specify a size of 1000 x 600; yet the map is only 300 x 150.

I’m not familiar with ArcGIS and am not the person who created the map itself, so I have no way of knowing if this is a problem with the map, the plugin, the shortcode, or the WordPress install itself (which is 5.2).