Application closes unexpectedly if plugin (loaded assembly) was processed with anti-debug protector.
I try it at huge project and i don't have small project to reproduce the issue.
Later, i try to build it.
After a small code digging I found, application close by code
if (OutputDebugString("") > IntPtr.Size)
Environment.FailFast("String"); //I added message to identify problem at log
Windows event log confirms it -

It normally reproduces at Windows 7 x64
I tried to run at two computers - my work computer and at production.
Conditions:
Win 7 x64, .NET 4.6.1