GUI Debugger ignoring some received packets

I'm developing an application connecting to Google's GCM CCS XMPP service using Smack 4.1.3.

In the application, I noticed some packets were not being logged by my `StanzaListener` so I fired up the GUI debugger and noticed that the `All Packets` tab shows my application receiving only 4 packets (acks) when I sent a total of 8 messages. I'm expecting to receive 8 packets (acks).

When looking at the `Raw Received Packets` tab, I can clearly see 8 received packets (acks).

Is there some sort of global packet filter that is catching a handful of these packets (acks)? Please let me know if I can provide any other useful information.

Thanks,

- Kyle