I set all the colliderProp nodes Thickness attribute from 1 to 0 (under the conversion attribute group) on the node.
I also remodelled the collision geometry (“bottom_geo”) as well as Container_geo so that their polygonal thickness was at least 1 Maya unit thick.
I took the boss mesh that is being used as the 4th motionField and meshProp4 geometry input and did an extrusion on it to give it some thickness (at least 1 Maya Unit thick). Since I extruded I had to reposition it by moving it down so it was somewhat centred with the Bifrost liquid main body.
On the 4th motionField itself, even though it was greyed out, I turned on ‘Enable Additional Velocity’ then zeroed out the x axis Additional Velocity. After that I turned ‘Enable Additional Velocity’ back off. This step shouldn’t make any difference but I did it for good measure/just to make sure.
I also disabled all the meshProperties that were connected to motionFields that were not enabled. Essentially just leaving the motionField4 and meshProp4 intact since they are being used with one another.
In order to get this all to work I had to uncheck all the cache and initial state attribute groups to assure it wasn’t looking/trying to load a cache file I did not have.
After this, when I did a playblast, I could no longer see the strange particle motion moving along x as was seen before.