I think there are some shenanigans going on with git lfs. I have a file which is not modified on disk as far as SourceTree and git on the command-line are concerned. However, Sublime Merge thinks the file HAS been modified, with the diff showing the lfs pointer file on the left and the actual file contents on the right. When I go to the repository in the command-line and run
git status however, Sublime Merge refreshes and no longer shows the diff. If I restart Sublime Merge, the diff re-appears.
It would also be great if there was a way to show the diff of the actual file contents rather than the lfs pointer. SourceTree allows this (we have some files in lfs that are occasionally quite large so they belong in lfs, but they are text and diffable and it's nice to be able to actually diff the contents).