Sourcetree/Fork not showing conflicts

Hello.

I am having issues with SourceTree and Fork showing conflicts. I am updating specific parts of a prefab that is also being used by another colleague albeit different parts than what I'm using. The bigger problem here is that when I merge into a fresh branch off of her branch it doesn't tell me there are any conflicts and then overrides her work with mine. Does anyone know why it isn't showing conflicts in the first place?

I have tried deleting and making a brand new clone of git. Tried merging and pulling into the new branch from my original branch. All with the same result. Even used the terminal git remote prune origin.

Thank you.