Unable to reduce keyframes / compress animations

I'm trying to compress some imported animations, I press the Apply button and watch the progress bar finish, but the option always reverts back to Off. I have no idea why, I've never had this problem before. To clarify, some animations do get compressed, but the majority do not.

I'll be investigating this further to see what the cause could be, maybe the files are set to read-only? I don't know, but in the mean time, I figured I would ask Unity Answers for any possible insights or solutions.

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Running Unity 5.2.2f1

The console outputs this message, even if I re-import:

 A default asset was created for 'Assets/3DAssets/NPC/Originals/NPC_grasshopper@idle.fbx' because the asset importer crashed on it last time.

 You can select the asset and use the 'Assets -> Reimport' menu command to try importing it again, or you can replace the asset and it will auto import again.

 UnityEditor.AssetDatabase:Refresh()
 FBXAnimationProcessor:OnPostprocessGameObjectWithUserProperties(GameObject, String[], Object[]) (at Assets/Editor/FBXAnimationProcessor.cs:13)
 UnityEditor.DockArea:OnGUI()