It appears that in UE 4.23, some specific arrays in construction scripts are no longer cleared automatically and retain references to TRASH objects from the previous construction script calls. This breaks some construction scripts which worked in 4.22 and earlier, and also is a regression.

Found in: 4.23.1 CL#9631420

Reproduced in: 4.24 CL#9745507 , 4.25 CL#Main

Link to user's test project:

[Link Removed]


Steps to Reproduce
  1. Create a blank project
  2. Create a new actor Blueprint
  3. In the construction script, add an "Add Hierarchical Instanced Static Mesh Component"  
  4. Add the HISM to an array 
  5. Out put the length of the array with a print string 
  6. place the actor in the world move it around 


Result: The array is not cleared with each update

Expected: Array to be cleared before the construction script is called again.

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ComponentUE - Gameplay
Affects Versions4.234.244.25
Target Fix4.23.24.24
Fix Commit9881378
Release Commit9881416
CreatedOct 28, 2019
ResolvedOct 29, 2019
UpdatedJan 25, 2021