Spring should have enough tension so it doesn't move around, neither the brake pads... maybe open it a bit so it has even more tension? Hydro disc brake calipers can be complicated to set up, maybe a mountainbike expert should have more experience to help you than a road mechanic?
I need to look at it myself so I know how to change pads on it. I'll get a new set of pads and work out how to change them. In the process I'll have a look at the spring. Maybe it's loose or something.
Don't have any experience with the shimano brake pads, but as everyone says... TRP brake pads are shit and investing in some Swisstop ones is really a great upgrade
Spring should have enough tension so it doesn't move around, neither the brake pads... maybe open it a bit so it has even more tension? Hydro disc brake calipers can be complicated to set up, maybe a mountainbike expert should have more experience to help you than a road mechanic?