Marion is not wrong... you might still need to wait another day or two for it to be registered as "default approved"
By our human counting, it appears 30 days have already passed. But sometimes computers have what's known as "off-by-one" errors (especially with calendar dates). So the computer may not think 30 days have passed yet.
So wait another day or two, to see if the computer catches up.
Otherwise, sometimes merges get stuck and never become default approved (perhaps due to the same bug). In those cases you can either get an admin to assist, or delete and re-propose the merge (and wait another 30 days).