My exported videos do not play when transferred

Hi all, today I tried exporting my my videos to the usual H.264 format, medium bitrate. It's my usual format. But today I've exported my video a hundred times and even has the correct extension, and it still won't play on any device when it's transferred. 

Whenever I export it and play it on my finder (I use an iMac), it plays properly as if there's no problem. But when I aidrop it on my phone, put it on google drive, email, wetransfer, etc., it doesn't play anymore and cannot be downloded/saved. It's all black and it seems like it's corrupted file—yet it is not the case on my desktop. I'm so frustrated, I've already restarted my premiere pro and worked around with different settings but it's still the same outcome. Does anyone know what's wrong?