Why I don't qualify for the American Opportunity Credit? Based on the most common reason provided I don't meet any of them.

If you are eligible, you have answered  something wrong*, in the interview. But, a lot of people are just not eligible. See https://www.irs.gov/Individuals/AOTC

A full time unmarried student, under age 24, is only eligible for the refundable portion of the American Opportunity Credit if he supports himself by working. You cannot be supporting yourself on parental support, 529 plans or student loans & grants. You usually must have actually paid tuition, not had it paid by scholarships & grants.  It is usually best if the parent claims that credit. 

You cannot claim a credit if you are, or can be, claimed as a dependent by someone else.

Grad students don't qualify for the AOTC.

Any times your parents claimed the AOTC, on your ed, while you were their dependent counts against your allowable  4 times.

*If you are under 24, you will encounter a question in the personal info section about supporting yourself with earned income.  Check your answer.  If you are 24+, you don't get that question.

Do you meet all of these?

• Be pursuing a degree or other recognized education credential
• Be enrolled at least half time for at least one academic period beginning in the tax year
• Not have finished the first four years of higher education at the beginning of the tax year
• Not have claimed the AOTC or the former Hope credit for more than four tax years
• Not have a felony drug conviction at the end of the tax year