The IRS says they send refunds in 21 days for 9 out of 10 efiled returns. The date is an estimate, an educated guess, a rough idea. In other words, it should not be relied on. The IRS can not say how long that other 1 of the 10 will take. All you can do now is, wait. Wait for the pay off of your interest free loan to the government. Did you believe that the IRS is omnipotent, omnibenevolen t and omnisc ient ?
Check out https://www.irs.gov/wheres-my-refund
Saying what is happening to your return at the IRS would be speculation. All you can do now is, wait. At least you know that the IRS has your filing. It does not matter who sent your form to them. That is the sole destination for federal tax returns. No one has discovered a way to make any tax agency speed up working on or sending out refunds. No one ever will because they are an overwhelmed, over worked, under funded and under staffed government bureaucracy. Eventually you will get the pay off of your no interest loan to the government. 21 days is just an educated/informed guess which should not be relied on.