Sometimes, MP4 files (mostly from a GoPro), MOV files, and AVCHD (MTS) files that are imported in Premiere Pro CC import without audio. The files are imported as video-only. You might also get an error stating "This File has no Audio and Video Stream" while re-linking files with these formats.
This issue affects Premiere Pro CC 2015.3 (versions 10.3 and 10.4) and Premiere Pro CC 2017 (version 11.0).
Solution 1: Clean Media Cache files
Delete all the files from "Media Cache" and "Media Cache Files" folders. The location of these folders can be found under Preferences > Media.
Note: By default, Media Cache Files and the Media Cache Database folders are stored in these locations:
Mac: /Users//Library/Application Support/Adobe/Common
Solution 2: Rename the Media Cache folder
Navigate to the Media Cache location and rename the folders to Media Cache Files_OLD and Media Cache_OLD respectively.
Solution 3: Move Media Cache to a different location
Change the location of Media Cache folders to elsewhere on your machine.