Yes, I use Gopro8 with Media Mod, it has HDMI output, then over to Hdmi grabber card into powerfull laptop.
Great step forward with the logfile, but it contains no recording session.
Please make a test recording over two till five minutes, then stop, then close obs.
Then reopen obs and use the menu in top to "upload
last log" or something similar. The log from the last run then contains information about your recording session including info, what may gone wrong.
What we can see from your actual log above is that obs is moaning, that there is still something fundamentally wrong with your camera capture:
17:44:47.575: Gopro 8: data.GetDevice failed
17:44:47.575: Gopro 8: Video configuration failed
Did you tried the grabber card by another software (bundled one or vlc player)?
And last question for today: Is your output size (1096x616) choosen by intention really? It seems quite unusual...