No Thumbnails in Search Results

Well, I took some time to trobleshoot your site today.

As you said, images are embedded inside the article in a very standard way. Therefore the placeholder '{"image_intro":"","float_intro":"","image_intro_alt":"",...' is not actually present in the HTML source of the article.

Something else is replacing the image filename with the placeholder, before rendering at a very early stage, thus preventing Custom Properties from fetching and resizing.

I can only have indirect evidence of that system at work without direct access to the code, but the effects are quite evident.
I also think I know which element is doing the replacing but, again, I can't do more troubleshooting without disrupting the website (and without a formal contract).

Anyway, Custom Properties is never going to work in your site, unless you make big modifications; I would advise against it. We'll contact you directly to discuss the next steps.

Tank you for the hint.
I tested everything and the component that made the conflict was Phoca Gallery.

If you install Phoca Gallery first and Custom Properties second, it will not work, the thumbnail error will appear.

But if you first install Custom Properties and Phoca Gallery second, there will be no more problems with thumbnails creation.

Strange bug, hope this helps someone with the same problem.

Thanks for the invaluable feedback. I'm glad to hear you managed to find a workaround.

I guess the problem is caused by the order in which plugins are evaluated.