She is not eligible for the refundable portion of the AOTC because she is a fulltime student, under 24, with less than half her own support coming for earned income.
Even though none of the 529 plan distribution is taxable, and therefore not "income", it is still "support"; just like money from a bank account.
Your conclusion is correct: you have to account for 529 distributions in the support test for dependent status and the support test for the refundable portion of the AOTC.
