I've tried to send 2 campaigns today, with an AB testing feature. 

I've set-up the campaigns as follow:

A/B Test Recipients:	A 30.0% Recipients  B 30.0%Recipients
Remaining Recipients:	40% Recipients
Winner Type:	Open Rate
Test Run Duration:	1 hour
Testing with:	Subject

I pressed "Sent" almost 2 hours ago, and the campaign is still processing. Some of the recipients got the email, but it seems that it's being sent to only a few people at the time.

Do you know where the problem might be coming from?

Thanks,

L.