There was an error for this 3T size. It looks like all other sizes are fine. I am SO happy you brought this up (well obviously you did since you were stuck), but I am so surprised nobody else has come in with this problem.
Anyway... here is the correction for Row 2. Rows 3-8 should then work out fine.
Currently in Version 1S and below:
LEFT BACK SHAPINGRow 2: Ch 1, sc in each sc across panel until last sc, work 2 (2, 2, 2, 2) || (2, 1, 2) sc in last sc, turn ––11 (12, 13, 14, 15) || (15, 15, 16) sc.
Rows 3-6 (3-6, 3-6, 3-6, 3-6) || (3-8, 3-8, 3-8): Rep 1-2 in that order 2 (2, 2, 2, 2) || (2, 2, 3) times, then
Sizes 2T & 3T only rep Row 1 once more and then Row 2 of Left Back. Fasten off––15 (16, 17, 18, 19) || (20, 21, 22) sc. Cont to Right Strap.
Corrections Now in Version 1T:
Row 2: Ch 1, sc in each sc across panel until last sc, work 2 (2, 2, 2, 2) || (2, 2, 2) sc in last sc, turn ––11 (12, 13, 14, 15) || (15, 16, 16) sc.
Rows 3-6 (3-6, 3-6, 3-6, 3-6) || (3-8, 3-8, 3-8): Rep 1-2 in that order 2 (2, 2, 2, 2) || (2, 2, 3) times, then
Sizes 2T & 3T only rep Row 1 once more and then Row 2 of Left Back. Fasten off––15 (16, 17, 18, 19) || (20, 21, 22) sc. Cont to Right Strap.
RIGHT BACK SHAPINGCurrently in Version 1S:
Row 1: (RS) Ch 1, sc in each sc across until last sc, 2 sc in last sc, turn––10 (11, 12, 13, 14) || (14, 15, 15) sc.
Size 3T Only:
Row 2: Ch 1, sc in each sc across, turn––15 sc. <-----DELETE
Sizes 3 mos (6 mos, 9-12 mos, 18 mos, 24 mos) || (2T, 4) Only:
Row 2: Ch 2, sc in 2nd ch from hook (increase made), sc in each sc across panel, turn––11 (12, 13, 14, 15) || (15, 16) sc.
Rows 3-6 (3-6, 3-6, 3-6, 3-6) || (3-8, 3-8, 3-8): Rep 1-2 in that order 2 (2, 2, 2, 2) || (2, 2, 3) times, then
Sizes 2T & 3T only rep Row 1 once more and then Row 2 of Right Back ––15 (16, 17, 18, 19) || (20, 21, 22) sc. Do not fasten off.
Corrections Now in Version 1T:
Row 1: (RS) Ch 1, sc in each sc across until last sc, 2 sc in last sc, turn––10 (11, 12, 13, 14) || (14, 15, 15) sc.
All Sizes:
Row 2: Ch 2, sc in 2nd ch from hook (increase made), sc in each sc across panel, turn––11 (12, 13, 14, 15) || (15, 16, 16) sc.
Rows 3-6 (3-6, 3-6, 3-6, 3-6) || (3-8, 3-8, 3-8): Rep 1-2 in that order 2 (2, 2, 2, 2) || (2, 2, 3) times, then
Sizes 2T & 3T only rep Row 1 once more and then Row 2 of Right Back ––15 (16, 17, 18, 19) || (20, 21, 22) sc. Do not fasten off.