Which GoPro model do you have? Triumph only tested the Hero 7 and only state it being "fully supported", and I have an 8 and a 9 and they both exhibit different issues. Both have the mode switch problem, in that if you try and cycle through modes it just goes straight to image mode and won't switch back. As I only use video mode, that's not an issue for me. The 9, however, has an extra glitch - it will let you start recording video but then you can't stop it. So I use the 9 on my helmet and control it manually, and use the 8 on my handlebars to capture back towards me.
I do have the GoPro remote so could conceivably mount that on the handlebars to control the 9 while I ride. Not how I typically record though, I tend to pick the part of the ride I want to film and talk to, fire up the cameras and go. I just go a GoPro Max 360 camera, so will see how that fares mounted to the bike...