Hi, I am not sure you are using any Visual Micro Arduino functionality. Atmel confused things some time ago when they released an Arduino importer. That converts arduino to cpp projects and does not use .ino files. This can diserable for some advanced users but moves away from Arduino.

If you do not have a project_name.ino in a project_name.cppproj in a folder of project_name then you certainly are not using Visual Micro.

For Arduino, we generally recommend vs2017 or 2019 with Visual Micro because the IDEs are more mature and Visual Micro offers more features.

If you follow the guide in yellow at the top of this page we will see if Visual Micro is making an Arduino compile or not. I suspect not, in which case your question is best answered by microchip on their support site.

Even if you are using arduino the import probably is unrelated. Arduino requires sources in the project folder, \src sub folder or any folder structure below the \src folder. To use external code Arduino would use libraries which are different to the atmel libraries.

In a visual micro project we can not prevent atmel studio from adding a Libraries node to the project, however the standard arduino build definitions have no way to use the atmel libraries. Visual Micro does allow .a files to be placed in a \libs folder otherwise you can use .c files but must be quite familiar with arduino code to use .c files.

If you want to create and compile a new simple project "file>new>arduino project" you will see what an arduino build looks like compared to an atmel build.

I think it is a question for the arduino.cc forum or the microchip forum. I can tell you that arduino and visual micro will not use the xml file and all other sourvces that need to be compiled (cpp/h) must fall into the allowed folder paths.

If you want it to work in Visual Micro then it should also work in the arduino ide.

Please provide the info requested in the yellow box above. It allows us to see what can't be found. You can see that info but we can't and you have not provided it.