The HLOD system gets stuck in a infinite loop when building. 

Comment from the user:

++I've tracked it down to this code:

const AActor* UHLODProxy::FindFirstActor(const ALODActor* LODActor)


auto RecursiveFindFirstActor = [&](const ALODActor* InLODActor)


const AActor* FirstActor = InLODActor->[Link Removed](0) ? InLODActor->SubActors[0] : nullptr; while (FirstActor != nullptr && FirstActor->IsA<ALODActor>())


const ALODActor* SubLODActor = Cast<ALODActor>(FirstActor); if (SubLODActor)


SubLODActor->[Link Removed](0) ? SubLODActor->SubActors[0] : nullptr;




// Unable to find a valid actor FirstActor = nullptr;



return FirstActor;

Working as expected in 4.19 CL# 4033788

Found in 4.20 CL# 4233996 and 4.21 CL# 4258917

This is a regression.

Steps to Reproduce
  1. Open the editor
  2. Enable the HLOD system
  3. Place a few meshes into the level
  4. Select them and create 4 HLOD levels with a Radius starting at 250 and doubling size each level
  5. Click Build on the HLOD window

The editor will hang around 70-75% but will never complete

The HLOD levels would generate

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ComponentTools - HLOD
Affects Versions4.204.21
Target Fix4.20.2
Fix Commit4282918
Release Commit4497729
CreatedAug 8, 2018
ResolvedAug 14, 2018
UpdatedOct 23, 2018
Pull Requests
4957 - TheCodez