'Unable to bind delegate' errors on packaging

I get two permanent ‘Ensure condition failed’ errors on project package:

1.MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: Ensure condition failed: this->IsBound() [File:g:\program files\epic games\4.12\engine\source\runtime\core\public\delegates\DelegateSignatureImpl_Variadics.inl] [Line: 1042]
MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: Unable to bind delegate to ‘ButtonNext_OnEndOverlap’ (function might not be marked as a UFUNCTION)

Note: It’s not just ButtonNext_OnEndOverlap, there are error messages for all Hit and Overlap delegates.

2.MainFrameActions: Packaging (Windows (64-bit)): UE4Editor-Cmd: Ensure condition failed: NewTransform.IsValid() [File:D:\Build++UE4+Release-4.12+Compile\Sync\Engine\Source\Runtime\Engine\Private\Components\SceneComponent.cpp] [Line: 415]

It started few days ago after update to 4.12, but first packages finished successfully. Then i tried to make a shipping package instead development - it was successfull too. But all later builds without noticable source changes failed. The problem can be related to this (https://answers.unrealengine.com/questions/427611/unable-to-bind-delegate-1.html), but i don’t use preprocessor macros. I also migrated all my content to entirely new 4.12 project (for another reasons), but still can’t package it. All builds in C++ in non-editor Development and Shipping configs are successful, and the project works without errors in editor and via Project Launcher.

Just checking but… you do have them marked as UFUNCTIONS?

UPD. I solved it. The problem was about lack of ‘class’ keywords near parameters in function definitions. Looks like Visual Studio doesn’t copy them from declaration on automatic definition creation via popup menu.