Failed to resolve System.Security.Permissions.SecurityPermissionAttribute

[mkeen31]

I have a solution with a .NET Standard 2.1 project that uses Xamarin.Forms and has a codebase that was originally intended for an Android/iOS application. I set up a separate .NET Core 3.1 project in the same solution that references the .NET Standard project as well as the Ooui.Wasm and Ooui.Forms libraries (both using version 0.14.16). However, when I try to compile my project, I receive an error that says "Failed to resolve System.Security.Permissions.SecurityPermissionAttribute". It points to line 17 of the Ooui.Wasm.targets file but I am unable to determine what the issue is. Anyone else having a similar problem?