If a QGIS project has a layer group set to visible==false, setting the visibility of the individual layers to true in QGIS-js does not render the layers on the map.

Steps to reproduce:

• Create a QGIS project
• Create a layer group with at least one layer, and set it to invisible (via the checkbox in the layer list)
• Open the QGIS project with QGIS-js (e.g. on demo site)
• Try to switch on the layer that is in the group

Actual result:

• Layer is not displayed on the map

Expected result:

• Layer is displayed on the map

Example:
(last two layers should render a choropleth map)