Error in Colour Layer when Rotating Group Object

Put an armchair asset with a shape tool applied 1 layer above the armchair using the "colour" blend mode and grouped them.

Rotating the group past a certain angle makes the colour shape disappear unless it is raised another layer. Further rotation eventually brings the colour layer back.

See my profile, Map: "Pondraker Mansion", Layer: "Second Floor Objects", Group: "Colourable Armchair" (repeatable for both of the green armchairs in the center room).