Hi Giuseppe,
I managed to re-produce the problem.
I have :

1) Adapter
itemName = "ALL"

2) Listener

3) SubItems (empty at the begining, we don't know when City will appear)
ALL/Lanciano
ALL/Aquila

- started the LS server and launchers
- started the browser as faster as i can
- clicka and ask for snapshot before any of cities has appeared
- when i use listener.Add("ALL", GetCurrentValues(true), false);
i get wrong order of events
- and it can't be repaired even if i reopen the browser

but if i use
_trueMarketListener.Add("ALL", GetCurrentValues(true), true);

i have no that problem !

It can be LS bug or i haven't found the best way to ensure that ADD precedes Updates for each subitems, ... subitems do the job even all the user unsubscribed "ALL", resubscribe "ALL", and so on ...

regards!