A random array is not consistent over a small sample.

Every time you complete a map, you have a 12% chance of getting the item, at most.

If you play once, and win, and get a rare item, and then play twice, and don’t get a rare item either time, that doesn’t mean your odds were 100% first time and 0% second time, you just didn’t get lucky. All that is involved is an 8%-12% chance.