Client didnt want to pay the 2020 balance due by direct debit, but wants the 2021 estimated payments to be paid automatically by direct debit...apparently ProSeries doesn't like that arrangement, kept kicking it back to me for a missing phone number, but all phone numbers are entered correctly.

At any rate, if this happens to you, just use  FTB WebPay and schedule your clients 540ES payments, its quick and easy and no hassles.  You get a nice completion screen with confirmation numbers for each payment!