JTAC not tasking me on to groups containing a single unit

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For various reasons I have a number of single unit groups in my missions (dynamically spawned in script). I find that an airborne JTAC (running a FAC Enroute task) won't task me on to them and I get the usual 'No further tasking available'. I discovered that if my group contains 2 or more units then the JTAC gives me taskings and appears to work fine.

 

This is either a bug or the way in which the JTAC is searching for targets. Could it be that a group with 2 or more units has a larger footprint and easier to find or is it simply that a single unit group isn't working correctly?