The solution provided by Emanuele worked for me. I could see the report when I accessed it directly from the server but when I used a ReportViewer control on my aspx page, I was unable to see the report. Upon inspecting the rendered HTML, I found a div by the id "ReportViewerGeneral_ctl09" (ReportViewerGeneral is the server id of the report viewer control) which had it's overflow property set to auto.
<div id="ReportViewerGeneral_ctl09" style="height: 100%; width: 100%; overflow: auto; position: relative; ">...</div>
I used the procedure explained by Emanuele to change this to visible as follows:
function pageLoad() {
var element = document.getElementById("ReportViewerGeneral_ctl09");
if (element) {
element.style.overflow = "visible";
}
}