Hi,
the lightbox on the Envira Gallery is not functioning. I have created one gallery(Wansfell) and it was fine.
Then two more(Todd Crag and Borrans) with exactly the same settings but neither show the lightbox.
Please provide the URL of each image for the lightbox to work. See attached image. It is working for Wansfell because the image URL field has content. You can access this when you click the i on each image. When you upload the image directly into Envira Gallery, the URL field will have content automatically. But when you select from already uploaded image from the Media Gallery you have to provide the URL.
Hope this helps.