Altium - Interactive Routing Tool not locking to component pins
It sounds like the track and the pin are on different nets. Make sure the two are connected in the schematic and make sure both show the same net. You can check the nets by double-clicking the track or the pin and looking in the properties window at the "Net" setting. If they are different, Altium will not let you connect them. They MUST be connected in the schematic in order for the routing tool to let you connect them using a track.