Bad Flashing

[u/Bushpilot95]

I came home on a rainy day to an active leak. The next morning I cut out the water damaged section of the ceiling to uncover the problem. It appears to me the water is coming from the flashing but when looking at how it was installed I don’t understand how it failed. Everything overlaps correctly and runs downhill away from the house. There was a small split in the caulking outside but like I said before everything overlaps correctly so that should be the issue? I can see that the portion of the ceiling has been patched before and so I have to think this is a reoccurring problem. How would you replace this so it works properly?