Entity Framework 6 is not mapping my columns correctly using Attributes

I am using EF6 to query data from a database. The database existed before the code and belongs to another application, so I cannot modify the database at all. I believe I am using a code first approach, even though the database already exists(Forgive me as I'm new to EF). The issue is that I am not able to pull back data for a column that is setup as follows;

[Column("ITEM_QTY")]
public decimal ItemQuantity { get; set; }

Now if I rename the property to ITEM_QTY, it pulls the data correctly. I'm not sure what I'm missing. I can pull data from any other field correctly, but this field returns 0 regardless of whats in the DB. Can anyone provide any direction?

In another discussion, someone had suggested a possible issue with the underscores in the column name. Not sure if that could be it, but adding for info. Thanks.

Edit: Adding code used to query database. Note that this was setup before I started working on the project, so following same convention;

var t = this.Database.SqlQuery<InventoryDb>("select top 100 * from COMPANY_INVENTORY with (NOLOCK) where COMPANY = @CompanyName",
                new SqlParameter("CompanyName", companyName)).ToList();