This is similar to an issue I ran into several years ago, and was working until just the other day. I'm assuming it's due to changes made on the site I am working with.

I am using version 2.53.0

For reference, here is what was discussed on Stack Overflow a few years ago: https://stackoverflow.com/questions/53037782/htmlunit-dynamic-content-not-found

Here is the sample code. Essentially no anchors are found nested under "react-drop-test".

` String url = "https://www.fangraphs.com/leaders/splits-leaderboards?splitArr=96&strgroup=career&statgroup=2&startDate=2021-03-01&endDate=2021-9-29&filter=IP%7Cgt%7C0&position=P&statType=player&autoPt=true&players=&sort=17,-1&pg=0&splitArrPitch=&splitTeams=false&groupBy=season";

	try (final WebClient webClient = new WebClient(BrowserVersion.FIREFOX_78)) {                                                                                                                                                                                                       
	    webClient.getOptions().setThrowExceptionOnScriptError(false);                                                                                                                                                                                                                  

	    HtmlPage page = webClient.getPage(url);                                                                                                                                                                                                                                        
	    webClient.waitForBackgroundJavaScript(50000);                                                                                                                                                                                                                                  
	    System.out.println("----------------");                                                                                                                                                                                                                                        
	    System.out.println(page.asNormalizedText());                                                                                                                                                                                                                                             

	    HtmlDivision div = (HtmlDivision) page.getElementById("react-drop-test");                                                                                                                                                                                                      
	    List<HtmlElement> anchors = div.getElementsByTagName("a");                                                                                                                                                                                                                     
	    for (DomElement anchor:anchors) {                                                                                                                                                                                                                                              
	        if ((anchor.getAttribute("class").contains("data-export"))) {                                                                                                                                                                                                              

	            HtmlAnchor leftyAnchor = (HtmlAnchor) anchor;                                                                                                                                                                                                                          

	            Page p = leftyAnchor.click();                                                                                                                                                                                                                                          
	            System.out.println();                                                                                                                                                                                                                                                  
	            System.out.println("----------------");                                                                                                                                                                                                                                
	            System.out.println(p.getWebResponse().getContentAsString());                                                                                                                                                                                                           

	            break;                                                                                                                                                                                                                                                                 
	        }                                                                                                                                                                                                                                                                          
	    }                                                                                                                                                                                                                                                                              
	}  `