"Error response during RestAction" when editing existing custom FFF on a Job Req

Summary:

Hi there,

We are on 25B (4 weeks in now), and have Redwood turned on for Recruiting and most other pages. We have found that our Recruitment team are just now facing the issue of the ""Error response during RestAction" when they try to edit a custom flex field in Details > Detail section.

It was working fine up until now. Any idea on whats causing the issue and which security or role needs to be added?

Note: We use a Custom Recruiter role.