Need a true expert for a small but tricky .NET C# task

It is more the job for some real expert ;-) I have a .net C# project, which is quite small and is finished but for some reason some antiviruses mark is as virus/malware etc, but everyone as different type. I will need an expert to look at it and to tell us (must explain us)what is causing this and fix it asap. So it is just a task to figure out why this happens, explain us and fix it earliest possible. For expert might be an easy one. It is the project for Visual Studio 2017. Community free version will work fine. It is a part of larger project so will not run by itself but if you take the [login to view URL] and upload to [login to view URL], you will see the problem: [login to view URL] So the goal would be to make it that the file will pass the antivirus [login to view URL] is nothing harmful by our opinion, it must be some coincidence with existing viruses or something like that.