to have a backdoor ROTH you need to have some non-deductible IRA contributions on the 8606, that makes the distribution on the 1099R non-taxable, one wipes out the other.

A conversion is a taxable event, you convert a traditional IRA to Roth and pay the taxes now, so when you eventually take the money out of the ROTH, you pay no tax on the basis or the earnings.

So what do you have?   Does the client have a non-deductible IRA basis on the 8606?