If people keeps talking after you close Yappari, when you start it up again you'll receive all the messages from the group when you weren't there. That's normal. You never leave the group, you just disconnect from it. When you reconnect you'll receive all the messages you didn't receive when you were disconnected.

If Yappari disconnects you stop receiving messages, that's also normal don't you think? If Yappari disconnects is because something's wrong with your connection (poor signal or something).

Also if somebody in your group is sending multimedia messages Yappari will disconnect because they aren't supported yet.

I don't understand why you need to clear the logs. You don't need to clear the logs to receive more messages, you just need to be connected. If Yappari disconnects is because the connection to the Whatsapp servers was lost. Yappari will always retry to reconnect every 30 seconds.

if you don't want to receive groups messages you have to leave the group, but there's no option for that yet hehehe.