HLOD generation problems

Hi everyone! Maybe someone had this problem before and could help me solve this. So, the problem is that when i’m trying to generate HOLD the engine goes through the process and when all done ( the process bar shows 100%) it crashes. Engine ver 4.20.3
I have simple scene - some trees and stones ( mid poly meshes - around 2k actors, with 20 - 2000 tris, and speed trees - 4k tris, ~50 actors). Materials are simple ( BC + spec). In project seettings ProxyLOD mesh rduction option selected. Substance plugin disabled.
After generate clusters process i have 250 clusters, and if i build proxy for only one from this list all works fine, but in all other cases - engine crashes.
Also if i delete some actors, and leave only f.e. 20 actors (4 HLOD clusters) - hlods are generated correctly

Error message:
Access violation - code c0000005 (first/second chance not available)

UE4Editor_Engine!UHLODProxy::GenerateKeyForActor() [d:\build++ue4\sync\engine\source\runtime\engine\private\hlodproxy.cpp:332]
UE4Editor_HierarchicalLODUtilities!FHierarchicalLODProxyProcessor::Tick() [d:\build++ue4\sync\engine\source\developer\hierarchicallodutilities\private\hierarchicallodproxyprocessor.cpp:112]
UE4Editor_Core!FTicker::Tick() [d:\build++ue4\sync\engine\source\runtime\core\private\containers icker.cpp:98]
UE4Editor!FEngineLoop::Tick() [d:\build++ue4\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3669]
UE4Editor!GuardedMain() [d:\build++ue4\sync\engine\source\runtime\launch\private\launch.cpp:166]
UE4Editor!GuardedMainWrapper() [d:\build++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:144]
UE4Editor!WinMain() [d:\build++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:223]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:283]