Is there a reason that my dependent care credit is showing with a max value of $1500, despite $8000 expenses?

One spouse has earned income well below $125K and the other was a full-time student for 10 months of the year, with no earned income at all. With over $8000  in child care expenses, at the 2021 expanded 50% rate for the refundable credit, I would expect a credit of nearly $4000. I think it would be slightly lower because the student spouse was only a full time student for 10 months. However, the credit shows as $1250. I tested the portal by increasing the dropdown for "How many months of the year was X a full time student?" to "12" to see the max value, to see if that was the reason it is so much lower. However, the credit was then only $1500. Am I missing something here?