The IRA company who sent you a Form 1099-R made an error in doing so. They have reported the trustee-to-trustee transfer, which is nonreportable, as if it had been a distribution paid to you. You'll need to obtain a corrected Form 1099-R showing $0 in boxes 1 and 2a to indicate that no distribution to you took place.
Since a non-spouse beneficiary is not permitted to roll over any distribution from an inherited IRA, TurboTax properly prohibits you from reporting any of the supposed distribution as having been rolled over. This improper Form 1099-R also wrongly implies that any of the money it represents that has been deposited into the new inherited IRA account is an excess contribution subject to penalty. So it's imperative that you get this corrected by the IRA company that issued the erroneous Form 1099-R.
A properly performed trustee-to-trustee transfer means that the money was never left the account in a way that gave you control of the money, such as in the form of a check made payable to you. The money must instead be made payable directly to the new IRA for your benefit.
