Undefined in caption when using gallery shortcode/lightbox

Hi there,

I’m using the gallery shortcode:

[su_custom_gallery source="media: 872,871,868,862,864,865,854" link="lightbox" width="200"]

However, when the lightbox opens, there is “underfined” instead of the caption.

I’m sure this is an easy solution. Can you help?

Thanks!

https://ww.wp.xz.cn/plugins/shortcodes-ultimate/