It actually looks like you’ve exported an over capture clip rather than a 360 degree spherical video and are now trying to reframe a non 360 video.
The reason I suspect you’ve imported an overcapture video is because of two things.
1 When you import a 360 degree spherical video into Premier Pro without the reframe plugin being used, you should be seeing something like this:
What you are looking at there is the front of a car and towards the edges the rear of the car. With your video, providing it was a 360 degree video without the reframe plugin being uses, you should have been able to see the rider, the front wheel of the bike, the rear wheel of the bike and the surrounding area. Instead all we see is a close cropped frame of the rider.
2 The two examples you used are the same picture. If you compare what’s visible in the first shot and compare what’s trying to be used once the GoPro Reframe Plugin is applied, it’s still the same picture. Handlebars, white and red top etc. So it’s trying to reframe a shot that’s not a 360 degree shot and that’s your issue.
So provide screen shots of how you’re using GoPro Fusion Studio, step by step, or use OBS screen recorder and upload the file to Youtube, might be able to stop where you’re going wrong and solve the problem for you.