ArgumentOutOfRangeException when loading a save file

[TheLeftExit]

Loading a save file (see attached) throws an ArgumentOutOfRangeException:

 	System.Windows.Forms.dll!System.Windows.Forms.ComboBox.SelectedIndex.set(int value)	Unknown
>	SA2 Save Utility.exe!SA2SaveUtility.CustomBehaviours.SelectedIndex(System.Windows.Forms.ComboBox c, int index) Line 25	C#
 	SA2 Save Utility.exe!SA2SaveUtility.MainSave.UpdateSave.AnonymousMethod__221() Line 683	C#
 	SA2 Save Utility.exe!SA2SaveUtility.InvokeChecker.InvokeCheck(System.Windows.Forms.Control c, System.Action a) Line 16	C#
 	SA2 Save Utility.exe!SA2SaveUtility.MainSave.UpdateSave(System.Windows.Forms.TabControl tc, System.Collections.Generic.KeyValuePair<int, System.Windows.Forms.TabPage> currentMain, byte[] save) Line 683	C#
 	SA2 Save Utility.exe!SA2SaveUtility.MainSave.GetMain() Line 42	C#
 	SA2 Save Utility.exe!SA2SaveUtility.Main.IsMain() Line 395	C#
 	SA2 Save Utility.exe!SA2SaveUtility.Main.Tsmi_Open_Click(object sender, System.EventArgs e) Line 268	C#
 	System.Windows.Forms.dll!System.Windows.Forms.ToolStripItem.RaiseEvent(object key, System.EventArgs e)	Unknown
 	System.Windows.Forms.dll!System.Windows.Forms.ToolStripMenuItem.OnClick(System.EventArgs e)	Unknown

SONIC2B__S01.zip

I see it's related to M1C declared in MainSave.UpdateSave, which seems to be related to cart mission info. I couldn't figure out much else. Can you take a look?

btw, your Discord handle (Froody#5824) doesn't seem to work