Question Unable to merge scenes using Smart Merge

I'm trying to set up UnityYAMLMerge with my Git project, but it fails to merge any scenes and prefabs
My .gitconfig:

I do `git merge`, which comes with some conflicts, then I run `git mergetool --tool=unityyamlmerge`, which gives the following output (snipped for brevity):

It also shows a popup with that error, seen below.


I saw some people on the internet recommend me change the mergespecfile.txt to point to Git's own merge tool for unknown files, but it seems it is assuming that the scene files themselves are tmp files and ignoring them, since if I set a fallback for tmp then I get the scene files on the fallback tool.
This means that using a fallback is the same as not using unityyamlmerge at all.