"Orphaned" pull request stuck in VSCode

[andriesdenhaan]

I have an odd problem. VSCode shows a pull request which is closed on Github, the code is merged and the dev-branch was deleted.
The item shows under "Local Pull Request Branches" in the "GitHub Pull Requests and Issues" extension, but there is no local branch or anything else that could remove this item from the "Local Pull Request Branches".

Does anybody have any ideas how to resolve this? I'm working with VSCode on macOS with the mentioned extension.