Hi @colin_mckibben - thanks for looking into this.
I’ve figured out the problem, so I was actually adding identities to roles using direct role assignment and revoking roles from identities using IDN Workflow (which like you said uses Access Request APIs), and that’s why we saw bad request error.
Whereas adding and revoking roles to/from identities using Access Request API and IDN workflow worked!
Thanks again mate! 