Hi,
I have two GPUs in my system, a 1080Ti and 3080. I use both for compute tasks, but I also use the system for gaming, where I want only the 3080 to be active. Certain games will default to the 1080Ti so I disable the GPU in device manager when gaming (actually I have a script for this, but that's beside the point). This works perfectly on its own - the ports continue to work, but games will not run on the disabled GPU.
The problem is, my monitor profiles seem to break in DisplayFusion whenever I do this. Applying any of the profiles causes the screens to flash black, then I get Error: Failed to call SetDisplayConfig [HR: 87]. I appreciate that this is quite an edge case, but is there any way to get DisplayFusion to continue applying monitor profiles when a GPU has been enabled/disabled?

I had a similar problem: Check
https://www.displayfusion.com/Discussions/View/monitor-configuration-profiles-getting-lost-and-not-working-after-different-setp/?ID=5451ac09-df21-497d-8934-9d351c0819f7
I ended up creating double the number of profiles for each possible configuration.
I guess the solution for you is to double your profiles, one normal with both GPUs and one only with the 3080. I took me a long time to try to solve this, not ideal but better than nothing. It is windows issue, how it attributes monitor numbers on different GPUs and DisplayFusion gets lost.

Sorry for the delay - I've attached the logs.
That's unfortunate if there isn't another way around this, I'm running low on macro keys haha. It would have been nice to be able to identify the monitors another way, but that's probably a lot of work for very few users. Thanks for the suggestion though, I will try separate profiles.
Edit: After some work, I seem to have got a decent setup. It isn't ideal, but it works fine with my scripts - thanks again.