Image Lightbox not working on Classic Themes with Gutenberg versions higher than 17.1.x

[liviopv]

Description

The Image Lightbox is not working on Classic Themes when using Gutenberg versions higher than 17.1.x. In the backend, the Image Block will present the "Expand on click" option, but in the frontend clicking on the image or in the icon to expand it will do nothing. No error is tracked in the browser console.

Switching to a block theme like TT4 or deactivating Gutenberg fixes the issue.

Step-by-step reproduction instructions

1. Install a Classic Theme
2. Install Gutenberg with a version higher than 17.1.x (I tested 17.2, 17.2.3 and 17.3)
3. Add an image to a page/post
4. Select the option to "Expand on click"
5. The image lightbox will not open on click

Screenshots, screen recording, code snippet

Video: https://cldup.com/qvnfo5aGOa.mp4 (bigger than 10MB)

Environment info

• WordPress 6.4
• GB 17.1, 17.2, 17.2.3, 17.3
• Twenty Sixteen and TT4

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes

[t-hamano]

Thanks for the report.

I was able to reproduce the problem you reported on Twenty Twenty-One. Apparently, the script is no longer loaded on the front end in the case of classic themes. Let's investigate the cause a little more.

[t-hamano]

I believe this issue is related to #56143. The possible cause is described in this comment.