I haven't been working with .NET for very long, but my experience is that mixing .NET Core and .NET Framework leads frequently to very confusing, inscrutable error messages about incompatibility between the two. Though if it builds it works fine.
The accepted method is convert projects to .NET standard and/or multi-target project itself. I haven't run into any issues but most of what I do is web projects, I wouldn't know if it was something like WPF.
