The reason is there is a bug on the request form that still hasn't been fixed. It's only saving one request -- if you just picked a first request and not a second, it's saving that first request in the second request field. If you pick two, it's only saving the the second request.
On my last visit I did get my requested section via online check-in -- I only made one request, it got saved (in the second request field) but they appeared to get that data and use it.
(So far no version of the online requests has been dynamic enough to know anything related to your reservation room type, what rooms are available, anything like that -- it's just static data on a form. That doesn't always work.)