Apologies for the confusion.
Illinois and Wisconsin have tax reciprocity, which means the income you earned from working in Wisconsin is only taxable to Illinois. Because of this, your resident state (Illinois) does not grant a credit for taxes paid to your nonresident state (Wisconsin). Since you had tax withheld for WI, you will need to file a return to get that money back. You'll need to allocate $0 of income to WI so you can get a full refund. Then file your IL return as if all of your income was earned within IL.
You'll get all of your tax back from WI and no credit on your IL return.
@MrJames25