Hi Paul,

First of all sorry for the late reply.

I can confirm you that the COMMAND mode seems to me the best choice for a scenario like yours. In fact it was specifically designed to manage dynamic lists or tables.
Unfortunately, however, there is no a tool that allows you to inspect the state of an Item maintained by the Lightstreamer kernel.
But, if you can reproduce the issue in a relatively isolated test environment, with a few client sessions, you could leverage these log settings

<logger name="LightstreamerLogger.pump" level="DEBUG"/>
<logger name="LightstreamerLogger.subscriptions" level="DEBUG"/>
<logger name="LightstreamerLogger.subscriptions.upd" level="DEBUG"/>

to try to understand what goes wrong, matching information about the updates received by the Data Adapter and those actually sent to each clients.
Indeed, if some rows are missing when the client asks for the snapshot the possible causes could be or your adapter has sent a DELETE command or a duplicate key case. But we can verify exactly with a log after having modified the settings as indicated above.

Regards,
Giuseppe