Npgsql dll working in Standalone Build but not in Editor

Hello. I'm currently using an Npgsql.dll which I have placed in my Plugins folder. I'm using it in two different projects. Both my projects work fine when built. The dll does its job and allows me to change my PostgreSQL database . The problem lies when I try to run the same scenes in the Editor.

For the first project, I get a MissingMethodException : Method not found : 'NpgsqlParameterCollection.AddWithValue . The weird thing is that a few lines before, sever methods from the Npgsql library have been called and they never produced an error.

For the second project, I got the same error if I use the same method. The game completely crashes though when I'm trying to read from the database.

As you can see, the problem is probably caused by the Editor being unable to access parts of the library. For anyone wondering, the import settings for the dll are at default to all platforms and it's targeting .NET 3.5. If you have any ideas on why this is caused, I'd greatly appreciate it since it's quite nerve-wracking not being able to easily check a debug.