csmVertexPositionsDidChange never resets Cubism3.0 Native

Hello,
I'm new to Live2d/Cubism programming and have a question regarding the Cubism 3.0 Core Native Development.

I integrated cubism to my project and implemented the rendering of moc3 files. Everything works fine but I got stuck at some point during the implementation of the animation system. I added the possibility to update the vertices if csmGetDrawableDynamicFlags has the flag csmVertexPositionsDidChange set. Unfortunately it is set each update frame. If I check the vertex data during debugging, everything looks unchanged (no animation is set yet). My character (and the vertex data) looks the same each frame but the dynamicFlag never gets a reset. I looked into the example from github and it is implemented like that:

// Update model.
csmUpdateModel(Sample.Model);
// Update renderer.
csmUpdateGlRenderer(Sample.Renderer);
// Reset dynamic drawable flags.
smResetDrawableDynamicFlags(Sample.Model);
// Draw.
csmGlDraw(Sample.Renderer, GetViewProjectionMatrix(), &Sample.Texture);

I implemented it the same way.
1. Call csmUpdateModel()
2. Update vertices if csmVertexPositionsDidChange is set (and more)
3. Call csmResetDrawableDynamicFlags for model
4. Render

If i do not call csmResetDrawableDynamicFlags alls flags for each drawable is 63 and it never changes (of course, because I do not call ResetDrawableDynamicFlag). If I call csmResetDrawableDynamicFlags after each update and before rendering the flags are always 33 and that tells me that the VertexPostionChanged flag is set all the time, even if I have no animations yet and the vertex data is the same. It is not a super critical problem because everything renders fine. But it is very slow because everything wants to update its vertex data each frame.

Did I miss something or am I doing it wrong?
Thank You.

Kind Regards
Nisi