I think radio stations are just waiting to find out that the general public are here for 5H and the song rather than just the core fan base which are obviously requesting a lot. I guess that's why the song is being a bit slow.
The audience decrease is only because it didn't make Z100's countdown like it usually does and KIIS didn't play it at night like it usually does. The spin increase is what matters; with spins, audience will eventually follow