OH 2.1 does not execute sendCommand

All,

I have encountered an issue and would like to verify if I am the only one.
After a few hours running smoothlessly, my OH 2.1 does not execute sendCommand anymore.

That means, if I trigger a switch (manually or in a rule) to set a state to OFF or ON, I can see the eventlog recognizing the command, but the state of the item does not change.

any idea?