The Karma will work in External Sync Mode when someone else is
sending it MIDI Clock. That is the purpose of the Sync Mode. When the
Karma is in INTERNAL Sync, it runs on its own clock, and you can send
that clock to external devices for them to “slave” to the Karma. When the
Karma is in EXTERNAL Sync Mode, it expects to receive MIDI Clock from an external device, and then it will “slave” to the other device.
If the KARMA Function and/or sequencer does not work when you are
set to EXTERNAL Sync Mode, then you are NOT sending it any sync,
even if you think you are. Check your MIDI setups, routing, manuals for
the other device that is supposed to be sending the sync, MIDI Interface
Clock filtering settings, etc.