All jobs have 'Terminated-Unknown' status and unable to cancel workflow

Hi all, I am fairly new to CircleCI and hope to get help regarding the issue mentioned in topic.

Context:

Pick up an existing project A in Bitbucket, having a config.yml set up previously with most content commented.

Issue:

However, when I uncomment the code and start to trigger the workflow, encounter jobs in workflow having status Terminated-Unknown.

I am unable to click the job and view details or cancel the workflow. The duration of the workflow continue to increase despite status of workflow being Failed.

Currently using the template Hello World config when setting up the project.

Tried stop building for the project A and setting up again, error persists.
Tried setting up for a new project B and re-setup for an existing project C, didn’t see the error occurs.

All help is appreciated!

Resolved.

Issue was caused by the Bitbucket API change, they released new APIs for only a few users.
CircleCI team promptly responded to the issue.

Thanks CircleCI team and Ito-san for your help.