This game never seize to amaze me...
After I cleared a level 4 cp I just could not call for reinforcements... I tried to log off and in but nothing. I haven't seen this bug yet but damn I have to be prepared for everything
Off topic:
I hope the raid patch will give us some purpose because i'm totally bored doing challenging/heroic stuff over and over again and i'm not interested in exotics, cosmetics or hidden stuff.
If you can't call for reinforcements it's possible there is already a group of friendlies on their way to try and take that control point. Open your map and check to see if there is a green gun icon moving towards the CP from somewhere else on the map. Sometimes they can come from pretty far away as well. It's extremely annoying and I usually avoid any CPs that are being attacked by another faction/friendlies unless they are already at the CP.