When you say iCam V3, do you mean iCam 2.0 (the latest version)?
There is a control to enable/disable Motion Detection in the latest version of iCamSource, but the iCam iPhone app doesn't have a control to enable or disable Motion Detection. It does have controls to enable and disable Notifications and Recording. Are you referring to the Recording control? If so, I'll try to replicate the problem and track down the cause.