Using 'Update Instance Transform' to rotate HISM instances will work in PIE, but won't work in a packaged game. This is a regression from 4.19.2 (CL-4033788).
This issue was reported and tested in 4.20.2 (CL-4302132). This has been reproduced in Main 4.21 (CL-4305553)
Results: Instances don't rotate in packaged game.
Expected: Instances rotate in packaged game.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-63242 in the post.
| 3 | 
| Component | UE - World Creation - Worldbuilding Tools - Foliage | 
|---|---|
| Affects Versions | 4.20.2, 4.21 | 
| Target Fix | 4.21 | 
| Created | Aug 22, 2018 | 
|---|---|
| Resolved | Sep 24, 2018 | 
| Updated | Jan 2, 2019 |