Spline points are not moved into sublevels if a segment of landscape is moved to a sublevel.
Regression (No) issue (does) occur in 4.10.4
If Persistent level is hidden> All spline points disappear, the sublevel landscape appears in level viewport, but splines cannot be edited.
If Sublevel is hidden> Wireframe of spline points is still shown in level, landscape components in sublevel are hidden from view.
If the sublevel is hidden, the spline points are hidden with it, if the persistent level is hidden, the spline points in the sublevel can still be edited.
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