question about DAE exporter tool

Thanks a lot for this great tool. 
I have a question about the DAE exporter tool. We have a model and a unity generated animation clip. The rotation curve on one bone is like this:

But after exported to .DAE file, the clip inside the newly generated DAE file is showing the same bone's rotation as: 

Only the yellow curve (Rotaion.y) is wrong. It's correct value is around 175, but several key frames have the value dropped to -175. And it has fewer key frames (automatic compression maybe?) I can send you a sample project if necessary. I am using Unity Pro 5.6.4 on a Windows 10 x64 PC. 

BTW, our goal is using some c# scripts to generate movement curves on one particular bone inside the Unity editor. Export to a .dae file, so it can be opened in Max or Maya. Then the artist can copy the curves back to the original model to do more modifications. 

I'd really appreciate it if you can take a look and maybe give me some hint about how to fix it. Thanks in advance.