Hi Torabi,
Sorry you’ve been beating your head against this. First, can you try switching the Additive Anim Type on all of your Aim Offset poses to ‘Mesh Space’ (instead of the current local space).
Also, I understand you are copying the shooter game setup where a regular blendspace node was used instead of the dedicated aim offset one, but using an aim offset node is the cleaner, better method. When shooter game was set up, those aim offset nodes probably didn’t exist yet.
Either way, your poses need to be additive Mesh Space.
Good luck!