Wrong keyframe values in animation preview of fbx and also after adding animation to animator controller

So I was exporting a model from Blender to .fbx.

The animation is quite complex since I baked a physics animation.

The animation works correctly in other softwares like the 3D-Viewer of Windows (and also when I reimport it to Blender).

The parts of the object which are not working are the ones that have a parent which is scaled to 0 during the export. Reason: They shall not be visible until the animation is played.

It does not work In Unity (see images).

How it is supposed to be after first frame:
alt text

How it is looking in Unity after the first frame:
alt text

As you can see, the scalings are completely messed up. I tried to play around with the import settings in Unity a bit. I disabled keyframe optimizations and “resample curves”. That didn’t help.

When I save the fbx animation as a separate file in Unity, I can even see that the keyframe values are all correct, e.g.- > 0 in first and last frame. And everything in between has a scale of 1. Though, when I add this animation to an Animator Controller of the GameObjects Animator, the values are again all over the place. The keyframes are the same, but the values are completely wrong.

What makes it even weirder is the fact that another previous animation works fine in Unity. And I am also just scaling a parent object from 0 to 1 in the animation.
So in summary: animation does not work with animator controller and in the animation preview of the fbx file. Keyframes seem to be correct when exporting animatio from fbx file, though are incorrect when added to an Animator Controller over an Animator script.