I can't edit or assign loadouts to any pawns, get the below error. Can anyone help?

This comes up in the debug log when i try to access loadouts:

Exception filling window for CombatExtended.Dialog_ManageLoadouts: System.NullReferenceException: Object reference not set to an instance of an object
at OreYields.StatPart_MassMultiplier.TransformValue (RimWorld.StatRequest req, System.Single& val) [0x00008] in <abf832d398484cee837a1dbbc4123660>:0
at RimWorld.StatWorker.FinalizeValue (RimWorld.StatRequest req, System.Single& val, System.Boolean applyPostProcess) [0x00022] in <f429400e900f434099af71800afbc07e>:0
at RimWorld.StatWorker.GetValue (RimWorld.StatRequest req, System.Boolean applyPostProcess) [0x0004b] in <f429400e900f434099af71800afbc07e>:0
at RimWorld.StatWorker.GetValueAbstract (Verse.BuildableDef def, Verse.ThingDef stuffDef) [0x00009] in <f429400e900f434099af71800afbc07e>:0
at RimWorld.StatExtension.GetStatValueAbstract (Verse.BuildableDef def, RimWorld.StatDef stat, Verse.ThingDef stuff) [0x00006] in <f429400e900f434099af71800afbc07e>:0
at CombatExtended.Utility_Loadouts.GetWeightTip (Verse.ThingDef def, System.Int32 count) [0x00015] in <9d6b112a60c645f7bac6b855cd226929>:0
at CombatExtended.Utility_Loadouts.GetWeightAndBulkTip (Verse.ThingDef def, System.Int32 count) [0x00032] in <9d6b112a60c645f7bac6b855cd226929>:0
at CombatExtended.Dialog_ManageLoadouts.DrawSlotSelection (UnityEngine.Rect canvas) [0x001d2] in <9d6b112a60c645f7bac6b855cd226929>:0
at CombatExtended.Dialog_ManageLoadouts.DoWindowContents (UnityEngine.Rect canvas) [0x0051c] in <9d6b112a60c645f7bac6b855cd226929>:0
at Verse.Window.InnerWindowOnGUI (System.Int32 x) [0x001ce] in <f429400e900f434099af71800afbc07e>:0
UnityEngine.StackTraceUtility:ExtractStackTrace ()
Verse.Log:Error (string)
Verse.Window:InnerWindowOnGUI (int)
UnityEngine.GUI:CallWindowDelegate (UnityEngine.GUI/WindowFunction,int,int,UnityEngine.GUISkin,int,single,single,UnityEngine.GUIStyle)