I "think" the IRS is holding those with the problem, rather than rejecting them (since people would just turn around and resubmit only to have them rejected again) until they fix the issue, then they will reject and the returns can be resubmitted without rejection.

I filed 3 returns on Monday, all accepted, 2 returns yesterday afternoon and only 1 got accepted, the other is stuck at IRS...so its not all returns that have an issue.