pending sending issue

Hi Guys

Anyone know the issue, campaigns out of the blue stuck in pending sending, checked and cron jobs are set up correctly

Set the cron to 200 campaigns and 50 subscribers at once and it sent the campaigns for 2 mins then back to pending

Did the same thing on setting 500 and 50 and again sent for a few minutes

I have PCNTL set to 50 50

I have tried all different combinations with no luck and running out of ideas so any help very much appreciated,