That's so unlucky with areas referencing a common master page! Killed a day to work around this to no avail.
Probably, the trick which looks being closest to achieve the correct 'area' token for master page is described here, that is, suggesting the following snipped inside master's OnPreRender:
var area = ViewContext.RouteData.DataTokens["area"];
ViewContext.RouteData.DataTokens["area"] = "";
base.OnPreRender(e);
ViewContext.RouteData.DataTokens["area"] = area
Sadly, it didn't work for me mainly because my ActionLinks are being generated not in a master directly, but in a sibling <asp:content/>, for whch page's original area is still used.