In this case there is some process interfering with JRebel. We need to find out What why and how is interfering.
To start deeper investigation then can you send jrebel.log in trace level with WAS thread dumps to support@zeroturnaround.com? These will be generated if you add JVM arguments -Drebel.log=trace -Drebel.log.dump_stack_traces=5
From the log we will look for what exact operation on what file JRebel was performing.
Can you also include output of command “jps -v” ? This lists all the JVM processes running at the moment and has list of most likely candidates Java processes interfering with JRebel.