Issues with importing videos into Premiere Pro CS6

Need a bit of help with something, been using Premiere Pro CS6 for around 7 years now, alongside using Premiere Pro 2020, but recently (like last couple weeks) whenever I download an MP4 and try to import it into a project file in CS6, it just says the file has no video or audio streams, but that same video imports fine into Premiere Pro 2020?

I just simply have been downloading a video and trying to import it into the project file and it has been giving that error message, or when it has worked it only imports as an mp3 with no video attached, is there something I'm doing wrong? I can provide a lot more info but its strange cause this is a recent development and hasn't happened before