Zone immediately unassigned in scene

[Fivebar]

Hi,
I am a new member to this forum and a new owner of a Fantom 08. I am having a few teething problems and I wonder if anyone here could help me with today's problem? :)

Sometimes when I assign a tone to a zone in a scene, and then save it, the zone immediately shows as unassigned. No matter how many times I do this.

But sometimes it works, or, sometimes two adjacent zones seem to become linked and swap in which one is assigned and which one isn't.

The fantom is connected to Ableton Live and I did have a problem with wayward midi messages coming from Ableton but I thought I had fixed that. Also, nothing is playing on Ableton when this happens on the Fantom. Any suggestions?