Thank you for giving me the opportunity to assist you. I will give the best answer that I can with the information provided.
This is a common problem with the IRS, where they have a code of 1201 or 1301 on the check your refund website and when you call, they cannot give you any information other than to tell you that they may have sent a letter or that they will send a letter.
There have been processing issues for certain returns, including the Form 5405 (homebuyer credit) payback.
Unfortunately, there is not much that you can do about this. The IRS generally will pay interest on a processing delay if they fail to issue the refund on a correctly filed return within 45 days.
The option to use when dealing with IRS delays is the Taxpayer advocate. They have a link to your rights in dealing with the IRS and other helpful info: