Do you actually see gaps on the waveform on the audio track or do you just hear intermittent dropouts?
Also, which phone is your video recorded on? How long are the video clips you're adding?
Have you ensured your computer has the latest version of Quicktime, per the program's system requirements?
The video was recorded on a Samsung Galaxy 6 and is about 30 minutes long.
I didn't see gaps in the waveform, I just hear intermittent dropouts as if the machine is having trouble staying current with the sound. Nothing similar with the video.
Is there a yellow-orange line along the top of the timeline, above your video clip, in Expert view?
If so, your video may be an MOV and the program may not have set up correctly to match your video clip. Try rendering the timeline (press Enter, the yellow-orange line will turn green) and see if the video plays more smoothly.
It's also possible that your didn't allow the program to completely conform the clip before you began editing it. A 30 minute video can take a couple of minutes to fully conform.
Is your video an MOV? Is there a yellow-orange line above it, along the top of the timeline?
Your thread starts with mention of cell phone video...cell phone video is characterized by variable instead of constant frame rate...but I see no mention of this very well known factor so far here.
There is another recent thread which includes video recorded with a device that records presumably with a variable frame rate. Today, the discussion there was not resolved until that variable frame factor was pointed to by someone entering the discussion already in progress.
Cell phones are known to record with variable frame rate. Premiere Elements does not fare well with video with a variable frame rate. The symptoms range from audio out of sync to not being able to import the video at all. Typical remedy - take the video into free HandBrake to obtain the H.264.mp4 with constant frame rate to take into the Premiere Elements project.
So, this factor should be explored - ruled in or out. If you want to confirm the variable frame rate condition before doing the HandBrake conversion, take the file into MediaInfo to read the file properties. If 3 frame rates are found instead of 1, then variable frame rate situation. Move forward with HandBrake. This has been written about by me and others frequently here and elsewhere.