The code in Box 7 for the rollover 1099-R is G.  The amount in Box 1 is much larger than Box 5.  This is because later in 2024, I rolled all of my pre-tax 401K contributions into a new Traditional IRA.  Box 2a has a value of 0.

If I answer 'yes' to the TurboTax question:

Did you move this money from a 401(k) to a Roth 401(k)?"

then later TurboTax asks me:

Did you make after-tax contributions to a 401(k), 403(b), or 457(b) plan?

to which I answer yes, and give the full after-tax rollover amount.

But neither Form 8606 Line 22 nor Line 24 get populated by TurboTax.

If I don't answer yes to the first question above, then the rollover amount is never asked about by TurboTax.