How to repair render above lead flashing

My property has a flat roof extension which joins the original house.

In a few spots the render is badly damaged just above the lead flashing.

It looks like the sealant in the photo was applied, ignoring the damaged render. In recent heavy rain we’ve noticed water ingress in the room downstairs.

I’m a competent DIYer, but I’m not sure what the correct fix is here. If I repair the render coming down over the top part of the lead, will it expand / contract at a different rate to the lead causing cracking and the same problem reoccurring?

How should the render repair meet the lead?