Look under the Analysis Settings. There is a category for Erosion Controls (or something like that). That controls when elements are removed from the model.  Have you tried changing those controls? By default, it will remove an element when the strain exceeds 1.5, but many elastomers can deform to much higher values of strain. Try turning that control off or use a larger value.  The benefit of having the element removed is when it gets too distorted, the time step gets really tiny and the simulation takes too long (or generates an error). Maybe if the elements stay in the simulation, the weight won't hit the floor!