In JON we can see changing statistics for caches without any problems. Monitoring looks to be ok.

Problems occurred while issuing any operation.
For example:

start cache issued on DefaultCacheManager (JON's popup exception window output):

java.lang.NullPointerException
at org.rhq.plugins.jmx.MBeanResourceComponent.loadBean(MBeanResourceComponent.java:175)
at org.rhq.plugins.jmx.MBeanResourceComponent.getEmsBean(MBeanResourceComponent.java:137)
at org.rhq.plugins.jmx.MBeanResourceComponent.invokeOperation(MBeanResourceComponent.java:524)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.rhq.core.pc.inventory.ResourceContainer$ComponentInvocationThread.call(ResourceContainer.java:634)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)

stop cache issued on cache

java.lang.NullPointerException
at org.infinispan.rhq.CacheComponent.invokeOperation(CacheComponent.java:190)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.rhq.core.pc.inventory.ResourceContainer$ComponentInvocationThread.call(ResourceContainer.java:634)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)

ISPN console with trace logging enabled says:

2013-01-25 15:24:27,351 DEBUG [CacheImpl] (RMI TCP Connection(8)-127.0.0.1) Stopping cache ___defaultcache on null
2013-01-25 15:24:27,357 DEBUG [TransactionTable] (RMI TCP Connection(8)-127.0.0.1) Wait for on-going transactions to finish for 30 seconds.
2013-01-25 15:24:27,357 DEBUG [TransactionTable] (RMI TCP Connection(8)-127.0.0.1) All transactions terminated

Other operations seem to be unavailable too.