Seems the TOGA inhibit was missed as discussed far, far earlier in this thread.
Ironically the FCOM procedure states, immediately after PM positions the flaps to 20,
Verify:
The rotation to Go-Around attitude
that the thrust increases
This section covers both the PF and the PM columns.
After that the PM column contains:
Verify that the thrust is sufficient for the go-around or adjust as needed
This is prior to calling positive rate. My personal habit is that being so close to terra firma then I will push the levers forward and expect my colleague to have his hands there as well to verify.
Sadly, albeit for probably many reasons, a poorly executed manoeuvre.