If you're playing it from a card reader it has to be a USB3 version in a USB3 (blue) socket.
If you don't havethat  just download it to the computer and try an updated player.
I find Windows Media Player is as good as any on my mid-range laptop - it plays 4K just fine, whereas VLC just locks up.

Since your screen won't be 4K you aren't seeing it as it should be anyway.
Save the file and eventually you'll get a 4K TV or monitor will show it properly!
It will still look better than 1080p HD though if you can get it to play.