Steps to reproduce: Create new UE5.5.3 project. Enable Async Physics Tick. Create a new C++ class with parent UNetworkPhysicsSettingsComponent.
Errors below
0>------ Building 5 action(s) started ------
0>[1/5] Compile [x64] CustomNetworkPhysicsSettings.cpp
0>[2/5] Compile [x64] CustomNetworkPhysicsSettings.gen.cpp
0>[3/5] Link [x64] UnrealEditor-NetPhysTest.lib
0>[4/5] Link [x64] UnrealEditor-NetPhysTest.dll
0> Creating object C:\Users\howeg\OneDrive\Documents\Unreal Projects\NetPhysTest\Binaries\Win64\UnrealEditor-NetPhysTest.exp
0>CustomNetworkPhysicsSettings.gen.cpp.obj: Error : LNK2001: unresolved external symbol “public: virtual void __cdecl UNetworkPhysicsSettingsComponent::InitializeComponent(void)” (?InitializeComponent@UNetworkPhysicsSettingsComponent@@UEAAXXZ)
0>CustomNetworkPhysicsSettings.gen.cpp.obj: Error : LNK2001: unresolved external symbol “public: virtual void __cdecl UNetworkPhysicsSettingsComponent::UninitializeComponent(void)” (?UninitializeComponent@UNetworkPhysicsSettingsComponent@@UEAAXXZ)
0>CustomNetworkPhysicsSettings.gen.cpp.obj: Error : LNK2001: unresolved external symbol “public: virtual void __cdecl UNetworkPhysicsSettingsComponent::BeginPlay(void)” (?BeginPlay@UNetworkPhysicsSettingsComponent@@UEAAXXZ)
0>UnrealEditor-NetPhysTest.dll: Error : LNK1120: 3 unresolved externals