I’ve seen a bit of 0x0000000000000008 related to landscape issues.
I’ve crashed twice with it while editing landscape, but haven’t seen the FRenderResource was deleted. That looks !!!
try a Build Landscape
Since your getting it usually on saving, a lot of landscape shader stuff uses the Windows Paging file, it could be helped by setting your Windows paging file to be as big as you can get, ideally not on the same drive as Windows or UEFN.
Maybe letting Windows manage the paging file size is doing something… do you have a physical drive Z ? If not it could be a paging file path ???