this happened a few years ago, they never were accepted and stayed in limbo hell. take my advise paper file these returns now or forever hear the wrath of your clients.
Paper file and have them end up in the 10 million pieces of unopened mail? that's ridiculous.
Yes, this has happened in the past and once IRS fixed the issue, they rejected the ones they were being held, and then they could be resubmitted and accepted.