Problem with Videos support needed

Hi, I have just bought the My Passport Wireless Pro and set it up with my Iphone 6s and the My Cloud App. When connected to the devices network I can properly upload pictures from my galery to the My Cloud App. Whenever I try to upload videos they seem to properly upload too, but the app doesn‘t show them. Sometimes I am able to upload videos and they show up, but some I am just unable to. I tried seperately uploading different videos and sometimes it works, but more often it doesn‘t. I feel like I can‘t really trust the device now with what it really contains or not, I definitely don‘t know what causes this problem. If you have any idea please just feel free to leave a comment…