1099R box7b for Rollover

I roll over some money form one IRA account to another IRA account.  The 1099R form I received have the money I roll overed in 1 and 2a, box 2b is checked for tax amount not determined, the box7 code is 7 and IRA/SEP/simple box is checked.  I checked code G in Box 7b using turbo Tax every year, but this year of 2023, when I do the error check, the TurboTax says: box 7b distribution code G is not appropriated based on the other code 7 entered in box 7a, please remove or correct this code.  

Why cannot I use code G this year for 2023?  

If I cannot use cod G, what code should I use to show this Rollover from one IRA account to another IRA account is nontaxable?