Thats your potential activity being "used up" , not a bug. You have posted in many activity periods.
Well, in fact I've posted in 2, maybe three activity periods. There's been a long period of complete inactivity between january 2014 and october 2015.
You have posted in 4 activity periods, you'll see the activity increase , stop after you reach 56 activity.
P.S: The thread's purpose has been fulfilled, would be a good idea to lock it to avoid unnecessary discussion( unless it will involve a lot of signature spam )
Edit: Those guys got before me, but still lock this thread now.