The rings can take some time to build, additionally, the defaults for the ring amounts are too high. A reasonable number for a powerful machine seems to be 1.5k or less particles. You can experiment to see what works best.
We've also discovered a bug that will cause the rings to take a long time to build, due to errors that are happening in the background. (essentially, there are cases when the ring has 0 mass) as you can imagine that's going to cause some problems
. That should be fixed in the next Alpha.