If Principal says that they have until 4/30 to file the Form 1099-R, it means that they requested an automatic filing extension that gives them until that date to file. Since 4/30 had not yet passed at the time that you spoke to the IRS, the fact that they had not yet filed the form with the IRS was not improper.
How is this causing you a problem? I don't see why there is anything that you should be doing about this yet.
