Why are issues auto-transitioning when a linked Bitbucket PR is merged?

[Christy Kennedy]

Hi all - I have a project that sees the problem described in the title every time a linked pr is merged on bitbucket.

The issues will auto-transition to the status "Cancelled" in our workflow.

Some things I checked: 

• Ticket history: History shows that the assignee transitioned the ticket to "Cancelled" (so not seeing an add-on user or "Automation for Jira")

• Workflow: no transitions have triggers, rules, or post-functions set up
• Bitbucket: no pipelines have been set up in the corresponding repo
• Automation: looking at the recent rule runs on the ticket, there have been no successful runs for the last week (this auto-transition happened today by the way)

any ideas? Note that we have jira cloud & bitbucket cloud