Deleting foliage actor from foliage menu removes actors from level viewport, but does not remove them from PIE until editor is restarted.
Regression (no) issue (does) occur in 4.11.2
Meshes in foliage mode remain in viewport during PIE
Meshes are removed from viewport during PIE
Note to testers: please test Undo/Redo of operations involving adding or removing foliage types or replacing foliage type with another one (right-click menu) including one that is already unpainted.
Head over to the existingAnswerHub thread and let us know what's up.