Are you the surviving spouse of the decedent?
One is not permitted to take a distribution from an inherited IRA and roll it over to another inherited IRA. Only a spouse beneficiary is permitted to roll over a distribution from an inherited IRA and the rollover can only be to their own IRA, not to an inherited IRA, claiming the IRA as their own.
The only way that one is permitted to move an inherited IRA to another inherited IRA is by nonreportable trustee-to-trustee transfer. With a trustee-to-trustee transfer, there is neither a distribution nor a rollover. So unless the transaction was actually a trustee-to-trustee transfer and the custodian of the original IRA issued the Form 1099-R by mistake, the movement of the funds was not handled correctly. If the custodian of the original inherited IRA mistakenly issued the Form 1099-R, you need to obtain a corrected Form 1099-R indicating that $0 was distributed.
Also, the information that you got with regard to RMDs appears to be incorrect unless you are a spouse beneficiary and you actually rolled the money over to your own IRA, not to an inherited IRA.
Bank and credit union front-office personnel are often inadequately trained with regard to properly handling this sort of transaction. Were the original custodian and the new custodian both the same credit union?
