Does anyone else have this?

During sex sometimes me and my SO will use a vibrator. I’ll use it in any position really, mainly in missionary, and it always feels the same. Good. But the second i get into doggy, nothing. I dont feel a single thing from the vibrator. Its like the clit goes numb. But if i change positions, it comes back. Its kind of annoying cause doggy feels really good and i wish i had the vibrator to use as well. Anyone else have this problem??