Push Notifications seam to be intermittent

Hey Guys!
I’ve been using ionic.io to handle push notifications, though for some reason it seams that not everyone gets the push notices. I’m probably sending out about 400 to 500 at a time and folks don’t get theirs at times, but others will.
I’m essentially running a parse job that queries the database and hits the ionic servers for push notifications.

Has anyone else experienced issues similar to this? Is there any throttle to the amount of notifications that can be sent at once?

Thanks for any guidance!