Bitbucket SCM Source Incorrectly Configured

I have had a number of pipelines that have been working successfully for years.

Recently, multi-branch pipeline scans consistently fail with a message:

The BitbucketSCMSource has been incorrectly configured, and cannot perform a retrieve. Check the configuration before running this job again.

Going into the Jenkins pipeline configuration and simply saving the config with the exact same settings fixes the pipeline, and it starts automatically picking up builds again.

However, after a couple of days of no builds, it enters the original state, giving the above error when scanning the pipeline, and the only way to get it starting again is to open and save the configuration.

Bitbucket Version: 8.16.1
Jenkins Version: 2.44.0
Bitbucket Branch Source Plugin Version: 856.v04c46c86f911
Bitbucket Server Integration Plugin: 4.0.0