You can use Studio to remove "fisheye" (And it works great) but you have to import a GoPro camera file for the [Fisheye Removal] option to show in the "Advanced" box.
If you import another file type, or modify the camera's original file, then import it into Studio, that option (Remove Fisheye) won't show in the "Advanced" window.
BTW: If you do process your file to remove "fisheye", try clicking on the [Protune] icon (in lower right) to enhance the video.
I makes a rather dull video "blossom out" Not for everybody, but some may like the effect? Worth a try!
Ageing Gracefully