Try my best to explain what is happening exactly…
we have an error with curly brackets in the url string because the curly brackets are not encoded.
_Lucee_utilProxy.prototype.addToRecent = function(idToRecent){return lucee.ajaxProxy.invokeMethod(this,‘addToRecent’,{idToRecent:idToRecent});};
and this is the returned string - method=addToRecent&returnFormat=json&argumentCollection={%22idToRecent%22:518378}&_679214599
and because the curly brackets are not encoded it’s throwing a 400 error.
Sorry probably not the best description of an error but i am a bit baffled by all of this.