Vertical diffusion for sediments module

Hello,I am using EFDC Explorer v10, and I am having some issues with the the vertical diffusion option in the sediment module:1. When I check the boxes for vertical diffusion for both cohesives and non-cohesives, the software automatically unchecks it for the cohesives, when I revisit the sediment settings, post run initiation.2. Checking vertical diffusion option causes the model to crash with a “error (72) floating overflow”. I tried reducing my time step to 0.5 sec (less than the recommended 0.6 sec through time step initialization). Thank you in advance for any help!Adithya