It is 371 now. Your activity is 370. It updates every 1 hour (maybe 30 minutes) and if you have potential activity, it increases.
I too have this problem. Now my post count is 58 and activity stopped at 42. Waited for 2 days still this problem persists. Did am doing any mistakes??
Have you made more than 14 posts since the Tuesday before last?
I'll only increase by 14 each time for a two week period. 42=14*3 so this is your third activity period, your next activity period doesn't start until next week (on tuesday) so you don't get anything until then.