Navigation System: registration queue full!

I’m getting “Navigation System: registration queue full!” error when cooking or building project and I can’t figure out why it’s started to happen… Anybody knows how to fix it, or where should I look?

UATHelper: Cooking (Windows): LogCook: Display: Cook Diagnostics: OpenFileHandles=20580, VirtualMemory=8489MiB
UATHelper: Cooking (Windows): LogCook: Display: Splitting Package /Game/LL_O/Maps/World_Map with class World acting on object World /Game/LL_O/Maps/World_Map.World_Map.
UATHelper: Cooking (Windows): LogWorldPartition: Display: WorldPartition initialize started…
UATHelper: Cooking (Windows): LogWorldPartition: Display: WorldPartition initialize took 3.05 sec
UATHelper: Cooking (Windows): LogWorldPartition: Display: GenerateStreaming started…
UATHelper: Cooking (Windows): LogWorldPartition: Display: GetPartitionedActors started…
UATHelper: Cooking (Windows): LogWorldPartition: Display: GetPartitionedActors took 28 ms
UATHelper: Cooking (Windows): LogWorldPartition: Display: GetPartitionedActors started…
UATHelper: Cooking (Windows): LogWorldPartition: Display: GetPartitionedActors took 299 us (total: 29 ms)
UATHelper: Cooking (Windows): LogWorldPartition: Display: GenerateStreaming took 144 ms
UATHelper: Cooking (Windows): LogNavigation: Error: Navigation System: registration queue full!
UATHelper: Cooking (Windows): LogNavigation: Error: Navigation System: registration queue full!
UATHelper: Cooking (Windows): LogNavigation: Error: Navigation System: registration queue full!
UATHelper: Cooking (Windows): LogNavigation: Error: Navigation System: registration queue full!
UATHelper: Cooking (Windows): LogNavigation: Error: Navigation System: registration queue full!
UATHelper: Cooking (Windows): LogNavigation: Error: Navigation System: registration queue full!
UATHelper: Cooking (Windows): LogNavigation: Error: Navigation System: registration queue full!
PackagingResults: Error: Navigation System: registration queue full!
PackagingResults: Error: Navigation System: registration queue full!

:black_small_square: Deleting only /Game/LL_O/Maps/World_Map helps, but that’s not the option…
:black_small_square: Deleting only Content_ExternalActors_\LL_O\Maps\World_Map helps, but that’s not the option…
:black_small_square: Deleting everything but leaving folders that had errors Content_ExternalActors_\LL_O\Maps\World_Map helps, but that’s not the option…
:black_small_square: Deleting only folders that had error and replacing them with backup version Content_ExternalActors_\LL_O\Maps\World_Map helps, but bug returned next day when I added 1 static mesh and deleted it… and now it is happening even in backup version where I did nothing…
:black_small_square: Deleting all folders in project folder and leaving only “Content” and “.uproject” did nothing.
:black_small_square: Deleting NavMeshes in World_Map did nothing.
:black_small_square: Deleting all actors in World_Map did nothing.
:black_small_square: Changing project settings for navigation did nothing.
:black_small_square: Setting navigation to null in world settings of World_Map helps, but that’s not the option…
:black_small_square: Reinstalling engine did nothing.