Git Blame annotations are empty

I've been using IntelliJ and Pycharm for months now. Since install my Git Blame annotations in the gutter have been broken in IntelliJ only.

In Pycharm, when the "Annotate with Git Blame" option is selected, the gutter is populated with the name of the author and the date of commit for each line in the source file. I can click any annotation and the associated commit will be opened in the git tab.

In Intellij this functionality does not work. When the "Annotate with Git Blame" option is selected, the gutter is highlighted with colours, but no Author names or commit dates are shown, and clicking lines in the gutter does nothing.

Other than this issue, the Git integration works as expected in Intellij. Above each method is a floating annotation giving a summary of Author names as shown below. I can commit, merge, push etc.

Below is a screenshot of my intellij gutter with git blame annotations enabled, followed by my pycharm gutter with the same enabled. I'd be most grateful if anyone could explain how I can get my intellij gutter to function the same as my pycharm gutter.
IntelliJ:

PyCharm: