Envoyer - Bitbucket integration issue

I have an Envoyer project that has been deploying successfully from a private Bitbucket repository for the last few years, as far I'm aware nothing has changed in the last month but the latest release produced the following error message:

Client error: POST https://bitbucket.org/site/oauth2/access_token resulted in a 400 Bad Request response: {"error_description": "Missing required field: refresh_token", "error": "invalid_request"} (View: /home/forge/envoyer.io/resources/views/scripts/deployments/CloneNewRelease.blade.php)

Which seems like an authentication issue, so I pressed the "Refresh Bitbucket Token" button under my account page, which didn't change things at all.

I should note that I do have full access to the repository but I'm only a collaborator on the Envoyer project, the person who is the owner is currently on holiday and is difficult to get in contact with.

So is this an issue that I can fix?