I just opened a support incident, number is 2873929.
Both Systems use .NET Framework version 4.5. I am going to check other details, like hotfixes.
When I compile the solution I get 10 error messages, one for every property definition. When I insert e.g. a space anywhere in the source 8 error message are removed from the output window. So there is a difference between compiling an syntax checking. (???)
My standard system is Windows 10 with Visual Studio 2015 and Visual Cobol 2.3 with Update 1 (vcvs2015_231.exe) and Hotfix (vcvs2015_231_hf01_125850.exe). Everything on this system works fine. I copied a WPF solution to the system of a customer and we got the ECM errors as described.
I also have a virtual PC with Windows 7. On this system I installed Visual COBOL for Visual Studio 2012 product trial (vcvs2012_23.exe). In this situation I got the same errors as on the customer system. Than I installed Update 1 (vcvs2012_231.exe from my support account) and the errors do not occur anymore. You will find the download E-Mail in the support incident. Also after Installing the Hotfix (vcvs2012_231_hf01_125843.exe) the errors do not occur.
This morning I asked my customer to check his system for update 1. I'm waiting for the answer.