The problem is related to and ACT-4118. I have tested the fixings for ACT-4117, on master branch (2016-03-09).
It doesn't work if you use a tenant id in deployment of processes an start the processes with that given tenant id.
I have copied the test case MessageEventsAndNewVersionDeploymentsTest to MessageEventsAndNewVersionDeploymentsWithTenantIdTest an inserted a tenat id in deployement and start. The test produce 12 failures. May be the same problem occurs for signals.
See attachement for test cases