Moved to the monetization forum.
Well yeah, ticking "monetization" simply means you're willing to have ads on your vids. It's then up to the advertisers themselves to decide.
As mentioned in other threads:
1)It's currently the first month of a new quarter so there is always a decrease in advertisers willing to advertise.
2)Lots of big advertisers have recently pulled their ads.
3)Some content isn't deemed appropriate for ads.