My morning house had LP panel siding originally. They installed Tyvek over that material and installed the vinyl over the Tyvek.

My concern is that the original windows were installed behind the original panel LP so there is no way to properly flash the windows to the new membrane. I pulled a couple of the viny pieces off at windows and found that the installers left about a 1" gap between the Tyvek and window frames, and of course there is no flashing anywhere around the windows. Since vinyl siding leaks, my concern is that now water is going to seep onto the LP sheathing and rot out the wall.

I am sure most of you have seen this-- what do you usually recommend?

There is of course the other typical retro fit installation defects with the new Tyvek where it does not run all the way to the base of the sheathing, where the sheathing (LP siding) is visible at penetrations, etc.