I still can not replicate it, you can even see a block isotopic layout on the demo here working without issues: https://ajaxsearchpro.com/load-more-infinite-scroll/
I tried to check your site too, but there is no visible search engine on the home page. Try re-installing the plugin manually, if that does not work, try a full plugin wipe as well – to make sure this is not some sort of a corrupted file or database corruption issue.
I will mark this as an issue, but since we can not replicate, I suspect there might be something else conflicting as well.