landscape glitch; visibility track in matinee and sublevels

hi!

I am having some issues with my matinee sequencer and sub levels. I have 9 sub levels under my persistent, I have made a visibility track in my matinee sequencer so that the landscape is invisible at the beginning and end of my video. But when I play the video the landscape is there the whole way through and is transparent and has hole/parts missing and weird triangles shadows : (bad image sorry)

In some cases the landscape wont appear at all if I want to edit it (sculpt or paint). I have tried to fix this by in the landscape manager changing the component size, selecting ‘resample’ and then click apply, that fixes it but as soon as I add it back to the matinee and goes back to the way it was.

I don’t know if this is linked and probably is an easy fix but I don’t know how to have may sub levels always loaded in 4.20. I was working on my landscape one day and I could see the map (image1) and when I reopened in the next day and load my sub levels, it was gone (image2). How do I fix this? HELP!

I done a lot of researching and can’t find anyone with the same issue, is there another way to go about this?

many thanks Holly