Rotating-drum with Mfix 2.3.1 doesn't run without any error

Dear Charles,
I found that once I uncheck this “pure granular flow”, the solver will report an error like this. Can you tell me how to solve this problem?
I would like to make one bottom side of the rotating drum enter the particle and the other bottom side expel the particle, and perform gas-solid reaction in it at the same time. Do you think this is feasible?
Thank you very much!