When an instance in a Hierarchical Instance Static Mesh component is rotated using "Update Instance Transform" it doesn't retain it's material's base color value when the material uses PerInstanceRandom.
NOTE: If the instance is also moved or scaled this repro fails.
WORKAROUND: If a very small number(0.0001f) is added to the transform location being updated then the initialized color is maintained.
Attached is a project that demonstrates this bug.
Found in 4.23 CL#9631420
Reproduced in 4.24 Cl#10570792, 4.25 Main CL#10611905
1. Create X number of instances in a HISM that are cubes.
2. Set the material of the instances to a material that creates a random color using PerInstanceRandom.
3. Create a call-in-editor function that only rotates the instances using the "Update Instance Transform" node.
Result: The instances are all black instead of whatever color they were initialized at.
Expected: The instances retain the colors that they were iniatilized with.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-85569 in the post.