Hi Amar,
Given the older version of Premiere Pro (CS6) you’re using and the nature of GoPro’s codecs, it’s likely that the issue arises from codec compatibility. Premiere Pro CS6 doesn’t natively support some of the modern codecs used by GoPro, especially the H.265 (HEVC) format.
To ensure compatibility and have a seamless editing experience, you will need to transcode your GoPro footage. This process converts the footage into something that Premiere Pro CS6 can handle more efficiently.
I recommend transcoding to the DNxHD or DNxHR family of codecs (ideal for PCs) as these provide high-quality performance while being less demanding on your system. This will help you avoid issues like slow playback or video not appearing properly.
You can use Adobe Media Encoder to handle the transcoding, which integrates well with Premiere Pro. However, if you prefer other options, HandBrake or Shutter Encoder can also do the job well.
Once your footage is transcoded, import it back into Premiere, and you should be able to edit without any issues.
Thanks, and good luck with your project!
Best regards!
Ivan Eldredge G.