We’ve noticed this issue and are actively working to gain a better understanding of it.
Please raise a new case online and reference the title of this article. To help us with our investigations please add to the description:
The affected Person ID.
The affected Workstep ID.
Redacted screenshot of the Provision and Contributions screen, clearly marking the element that becomes incomplete.
What inputs are 'REQUIRED' to make that element complete again, so that updating contributions can be attempted again.