Video Not Saving to iPhone (from PC) Incompatible file?

Hi all,

Hope you are well. 

My workflow is usually editing from a PC, posting to Google Drive then downloading on my iPhone from there so it can be saved in my camera roll. The reason being is when the video made is in my camera roll, I can post it on social media platforms. 

Usually, this works without a problem. This particular video though keeps giving me problems. When I try to save into the Files application on my iPhone, it won't play like all the other videos I've made. I even went on an imac and tried airdropping the video, only to get an error saying "unable to save, save in Files instead?" 

I exported in H.264 (like all my other videos). I tired exporting in Quicktime format (.mov) but didn't do anything. The *only* thing different about this video is I've downloaded all the footage used off of YouTube, whereas usually I'm editing videos I've shot from my phone.