I think wordings of IP1 also depends on category. I had IP1 message which you have mentioned here for IP2. Probably bcoz I'm Fsw-O with Canadian exp.Hi.....after going through previous threads i finally came to know that for IP1 :Your application is in progress. We will send you a message when we start your background check"
Then it will be NA and last before PPR will be IP2:We are processing your background check, we will send you if we need more information"