Normal are different after Merge Actor on scaled objects

Normal are different after Merge Actor on scaled objects. If the actors aren't scaled, the issue doesn't seem to occur.

A licensee is trying to use the Merge Actor tool to optimize their entire project but this issue is keeping them from using the tool.

This is a regression:

Working in 4.17.2-3658906

Not working in 4.18.3-3832480

1. Open the attached test project in 4.18+
2. In the Viewport, change to Unlit mode
3. Take a screenshot of the 2 rocks
4. Select both rocks > Right-click > Merge Actors
5. Enable the checkbox at the bottom to Replace Source Actors > Merge Actors > Save
6. Take another screenshot of the actors after merge
7. Compare the normals in both screenshots

Results: In 4.18+ the normals will be different after the merge

Expected: The same behavior as 4.17 where the normals are identical