try to use animationclip.SampleAnimation get problem

I use for loop to sample child transform result sample part of sub gameobject,other transform not change.
IF i use SampleAnimation in update function,all transfrom get sample properly.

Code (CSharp):

1. Dictionary<string, List<Matrix4x4>> m4 = new Dictionary<string, List<Matrix4x4>> (14);
2.         for (int i = 1; i < boneMatrices.GetLength (0) - 1; i++) {
3.             float t = (float) (i - 1) / (boneMatrices.GetLength (0) - 3);
4.             clip.SampleAnimation (renderer.gameObject, t);
5.             for (int j = 0; j < bones.Length; j++) {
6.                 var tr = bones[j];
7.                 List<Matrix4x4> samebone;
8.                 var cmt = rootbone.worldToLocalMatrix * tr.localToWorldMatrix * bindPoses[j];
9.                 if (m4.TryGetValue (tr.name, out samebone)) {
10.                     if (samebone.Contains (cmt)) {
11.                         samebone.Add (cmt);
12.                     } else {
13.                         samebone.Add (cmt);
14.                     }
15.                 } else {
16.                     m4[tr.name] = new List<Matrix4x4> () { cmt };
17.                 }
18.                 boneMatrices[i, j] = cmt;
19.             }
20.         }

sample in for loop

Code (CSharp):

1. delt1 += Time.deltaTime;
2.         var clip = AC[0];
3.         var mtx = sampledBoneMatrices[0];
4.         int framid = (int) (clip.frameRate * ((delt1 > 1 ? delt1 = 0 : delt1)));
5.         float t = (float) (framid - 1) / (mtx.GetLength (0) - 3);
6.         clip.SampleAnimation (target, t);
7.  
8.         NativeArray<Matrix4x4> boneTransforms1 = new NativeArray<Matrix4x4> (mtx.GetLength (1), Allocator.Temp);
9.         for (int i = 0; i < boneTransforms1.Length; i++) {
10.             var finalmatrix = rootBone.worldToLocalMatrix * bonestran[i].localToWorldMatrix * BindPoses[i];
11.             if (!bonesmtx.Contains (finalmatrix)) {
12.                 Debug.LogError ($"not find {bonestran[i].name}  bones corresponding mtx[framid,i]\n{mtx[framid,i]} fram={framid}");
13.                 //  boneTransforms1[i] = finalmatrix;
14.  
15.             }
16.             boneTransforms1[i] = mtx[framid, i];
17.  
18.         }

sampled in update function.
Anyone konw what's happened?

 

call for unity team