I have set up a simple rig with IKs and am not able to keyframe the bones properly. Although I select all bones before keyframing it, it seems that I'm not able to animate any bone after frame 30. Is this a bug? I currently use Blender 2.78 a.
You have converted your action to an NLA strip. Outside the range of the NLA strip the action is no longer shown.
- Go to the NLA editor. Select the strip. Press X to delete it.
- Go to the Dopesheet. Set it to Action Editor mode and choose the action you were working on (which we just deleted in the NLA editor). Now you can work on the full action again.
You probably pressed this button, then continued to edit your action.