There is an extra ‘yo’ on patt round 5, which is throwing out round 6, the instructions for patt round 6 is correct.

The correct pattern instructions should be as follows:
Patt round 5: (K2tog, yo, K1, K2tog, yo twice, SSK, K1, yo, SSK, P3) 10 times, SSM.
Patt round 6: (K4, K into front and back of double yo on previous round, K4, P3) 10 times, SSM.

I do apologise for the inconvenience caused, despite independent pattern checking the odd mistake still creeps through.