So the file is 'up there' and not local? That could likely be the cause.
I and a partner are working online through LucidLink ... which does a magical job of providing online video file usage. He's in Cape Town SA, I'm in Oregon/USA, and our LucidLink filespace is in London. He loads a folder of media, I see the folder in less than a minute on the virtual drive on my computer. Shortly after that, I can actually import the files into PrPro and start working away.
Totally puzzled as to how they do this, as we've tried that with we-transfer, dropbox and a couple others, didn't even come close to this kind of performance.