Open image in posts in lightbox popup

There are two forums, different versions, but the settings are the same. On one, images inside a post open in a lightbox on click, on the other they don’t.

For example, everything is fine here (version 2.6.5):

Here images do not open on click (version 2.7.7):

The forum settings are the same. What could be the problem?

Refresh topic because have no answers… ((((

Is it because they’re running different versions of Discourse?

Admins say that when the versions were the same for both forums, there was the same behavior.