Brew kettle bottom jacket

Having difficulty with the bottom jacket on a brew kettle not heating properly. This is a new system that was just fired up all other jackets are performing fantastic. The top jacket of the kettle is working great bottom jacket is not. Bottom jacket has inlet and outlet at same elevation, steam solenoid valve has been checked and is working, wye strainer has been checked and is clean, steam trap has been checked and is clear of debris. Boiler is high pressure operating at 40 psi, which is then knocked down to approx 11.5 psi after the PRV valve. Condensate is pumping back to boiler as intended also. Appreciate any thoughts suggestions