Patience, Grasshopper...
I went through the same thing about a year ago. Flew DCA-SEA-BLI and back on AS and Horizon (AS Connection). It took almost two weeks for the flights to appear in my NW WP account. As previous replies indicate, it does longer than we're typically used to, but as I recall when I posted a similar question on the WP forum no one said they didn't get their miles posted eventually.