rotating machinery, conical subdomains

Hello

I'm trying to model a rotating impeller in a tank that has a conical shape, like a crucible. The Reynolds number is low. The model doesn't converge, but when I change the tank to a cylinder (both the outer subdomain and the inner rotating subdomain), it does run. I have tried making the inner subdomain both conical and cylindrical, but none of those work. Any chance someone could give a look and let me know if there are any ideas of what could be wrong in my model?

Thank you so much,
Sylvana