I can repeatably hang Live (or, if a MfL Device is open for editing, hang both Live and Max) by sending a message from Java in overdrive which is pushed out through Live as a controller message. Inspecting the LEDs on the output device suggests that no MIDI is emitted.
Everything is fine if I do the same in the UI thread (i.e. using "outlet" rather than "outletHigh"). Everything is fine if I run the overdrive version of the patcher in plain Max rather than as a Max for Live device.
I’ve not tried this outside the Java world. I can prepare an example if necessary (it’ll take a little while to do a pure MXJ version since I’m actually calling in from Jython; if anyone is running my Jython package I can quickly prep something in that).