Lightbox doesn't work

hey,

i just installed your plugin and it works fine with the “the-7” theme, that i use. i set up a test page, to try all the options, but though i chose the “open video in a light box when clicking the featured image” in the plugin media settings, i just get directed to the post.

am i missing something?

best regards
philipp

https://ww.wp.xz.cn/plugins/featured-video-plus/