This is due to your Iphone recording being single-track MONO. When a stereo track is added, the MONO element moves to the left channel.
The issue may be corrected in the most recent VP versions. Download here.
Or, fix it this way...
Right-click your Iphone clips, individually, and SAVE AUDIO CLIP AS NEW FILE. They should be in your PC's Music folder.
Load each clip, individually, into Wavepad.
If the button at the bottom of the window reads MONO, click it and choose STEREO.
Convert the file and FILE|SAVE AS as a .wav type by the same name.
Import the file into VP and replace the original with the new file.