So in my repository I have a branch called patch that I created from master in which I committed 6 commits. Then I created a pull request from patch in order to merge it to master. The pull request has been approved and when I merged it into master in Github using create merge commit option (which is the default option), strangely the merge created only one commit in master containing all the changes from the pull request's 6 commits, as if I had chosen squash and merge option (which I had not).
So I don't really understand what's going on with my repository. create merge commit option is supposed to merge the branch into master with all the new commits + an additional merge commit, but it's not behaving this way and I don't know why.
And What is even stranger is that create merge commit works fine in my other repositories. So I guess there is an option in this repository's settings that makes this problem occur, but I don't know where to look at.