LogUObjectHash: Error: Internal Error: RemoveFromClassMap NumRemoved = 0 from object list for UserWidget

Why would that happen during loading the map after going to main menu?

[2019.10.13-16.07.28:620][607]LogNet: Browse: ***.***.***.***:7958//Game/GameEntry?PlayerToken=********************?PlayerName=yuyu51
[2019.10.13-16.07.28:620][607]LogTemp: Display: ParseSettings for GameNetDriver
[2019.10.13-16.07.28:620][607]LogTemp: Display: ParseSettings for IpNetDriver_6
[2019.10.13-16.07.28:620][607]LogTemp: Display: ParseSettings for PendingNetDriver
[2019.10.13-16.07.28:621][607]LogInit: WinSock: Socket queue 32768 / 32768
[2019.10.13-16.07.28:624][607]PacketHandlerLog: Loaded PacketHandler component: Engine.EngineHandlerComponentFactory (StatelessConnectHandlerComponent)
[2019.10.13-16.07.28:624][607]LogNet: Game client on port 7958, rate 10000
[2019.10.13-16.07.29:475][660]LogHandshake: SendChallengeResponse. Timestamp: 8.264072, Cookie: 171050219015238229159236072076218168145019013138216088201212
[2019.10.13-16.07.30:491][723]LogHandshake: SendChallengeResponse. Timestamp: 8.264072, Cookie: 171050219015238229159236072076218168145019013138216088201212
[2019.10.13-16.07.31:460][783]LogNet: UPendingNetGame::SendInitialJoin: Sending hello. [UNetConnection] RemoteAddr: 35.229.16.185:7958, Name: IpConnection_6, Driver: PendingNetDriver IpNetDriver_6, IsServer: NO, PC: NULL, Owner: NULL, UniqueId: INVALID
[2019.10.13-16.07.31:830][806]LogNet: Welcomed by server (Level: /Game/Main, Game: /Game/Blueprints/GameMode/BP_GameMode.BP_GameMode_C)
[2019.10.13-16.07.31:831][806]LogLoad: LoadMap: ***.***.***.***:7958//Game/Main?PlayerToken=*************************?PlayerName=yuyu51?game=/Game/Blueprints/GameMode/BP_GameMode.BP_GameMode_C
[2019.10.13-16.07.31:889][806]LogUObjectHash: Error: Internal Error: RemoveFromClassMap NumRemoved = 0 from object list for BPW_ComboBoxSettings_C /Game/Blueprints/UI/Game/Options/BP_Widget/WBP_OptionMenu.WidgetArchetype:WidgetTree_0.VSynch_BPW_ComboBoxSettings
...
[2019.10.13-16.08.30:736][806]LogWindows: Error: Assertion failed: NumRemoved == 1 [File:C:\Unreal\UnrealEngine-4.22.2-release\Engine\Source\Runtime\CoreUObject\Private\UObject\UObjectHash.cpp] [Line: 665] 

Game is in shipping configuration. Happens from time to time.
I blame long names in this widget, but is it really the case?

Crash is related to GC most likely and it’s huge bug. More info here: Garbage collection crash. - C++ Programming - Unreal Engine Forums