Be sure you have your input set to either the LEFT or RIGHT input from your interface and NOT the stereo input. Chances are good that you are using one output from the guitar processor/amp and you are putting it into one of the two channels on the interface and have the track input set to stereo input, vs using the correct Left or Right input in the track to match your physical input.
If you record with the STEREO input, it will send the signal to one side only. The result is exactly what you are describing. When you send it in to the RIGHT or LEFT input, it makes a mono track. You will hear the playback on both sides equally and you will still be able to pan it left or right in the final mix.