Hi,
Thank you for the details!
Interestingly, the MySQL log refers to a syntactical error, when there is none in the log, so maybe there is a missing part. I am suspecting the file may have been corrupted, it can happen if it was uploaded via FTP.
- Can you please try downloading the plugin from codecanyon, then uninstalling, deleting and installing it again? That will refresh the files. Your settings, search instances etc.. will remain as is.
- Try turning OFF the custom ajax handler too, that may cause conflicts in some cases.