[-mAx-]

you have to increase complexity of your model step by step.
I don't understand where comes fluid in.
Any way
First concentrate you on the sliding mesh.
What is the surface (white) which is in the middle of your domain, but not splitting the whole domain?
Then if you only have your red mixer which is rotating, forget stationnary etc...
you only have to work with interfaces.
Define the red generated surface as interface 1 and the white generated surface as interface 2.
Define the red rotating volume as separated fluid domain, for being able later to define it as rigid body in Fluent
When moving back your rotating (red) volume, then interface 1 and interface 2 should be superposed.
Only connect them back in Fluent by defining grid interfaces.
Once your mesh is well rotating, and fluid isn't stopped at interfaces, then introduce vof