original title: Some of the ui material change to "stencil id:1, op:keep, Comp:Equal" usually they were "Defalut UI Material (Material)" they are Images with no material. The problem is tmpTexts under these Images can't be seen. I tried : remove the Image, and add component image ,text can be seen but it change to "stencil id:1, op:keep, Comp:Equal" while on play , then text can't be seen befored all these happened: I was using ctrl+z , then got the error below. Switched another scene then found this problem. error: InvalidOperationException: Sequence contains no elements System.Linq.Enumerable.Last[TSource] (System.Collections.Generic.IEnumerable`1[T] source) (at <a6e6599e603241b58034b5ba39fef2ac>:0) UnityEditor.Graphs.AnimatorControllerTool.UpdateStateMachineSelection () (at <1d4681f7b1d74362928faef31b1df1aa>:0) UnityEditor.Graphs.AnimatorControllerTool.RebuildGraph (System.Boolean updateSelection) (at <1d4681f7b1d74362928faef31b1df1aa>:0) UnityEditor.Graphs.AnimatorControllerTool.UndoRedoPerformed () (at <1d4681f7b1d74362928faef31b1df1aa>:0) UnityEditor.Undo.Internal_CallUndoRedoPerformed () (at <b1863331a9da4cebb6cd21df9a943f93>:0) UnityEditor.EditorApplication:Internal_CallGlobalEventHandler() (at ?) edit: It seems it is control by mask component. Maybe I changed some value of the textmeshpro shader, then caused text not showing under mask. still want help : how to reset textmeshpro shader? I forgot which value I changed. edit: I use my backup font asset to replace the current one, things are now alright. Main problem solved still want to know which value of tmptext (shader or font asset?) changed will cause this issue: text not showing under mask.