In UNICAST/UNICAST2, a connection reaper closes idle connections after conn_expiry_time ms. The closing of a connection from A to B simply destroys and removes the entry for B (on A).
However, if there are pending (unacked) messages in B's connection entry, they will be dropped.

SOLUTION:
Instead of simply destroying the connection entry for B, we should mark the entry as 'closing', so no more messages are added, and flush any pending messages. Perhaps send a CLOSE message to B.

WORKAROUND:
Set UNICAST(2).conn_expiry_time=0. This doesn't run the connection reaper