I recently purchased a home in Melbourne, Australia and have had a persistent leak which enters at the corner of this skylight during significant rainfall.

The first photo shows the original condition of the roof, and then the second, third, and fourth photos are after I have done periodic repairs with a flexible flashing.

After a few further rain events, the issue seemed to improve a bit, but the leak is still occurring. The fifth photo shows the rest of the roof upstream of the skylight, and there’s obviously some joints there in pretty bad shape. Is anyone able to comment on the likelihood of water entering further up at one of those deteriorated joints and travelling down, or any other potential entry point?

I’m at the point where I don’t necessarily mind sealing up the other joints, but then if that doesn’t work I don’t want to have done all that work if there is another more obvious cause.

Thanks