Disassociating a policy project means Gitlab will silently ignore it when re-applied for existing MRs

Summary

Projects seem to silently ignore previously applied security results policies in external policy projects once applied=>unapplied=>reapplied. The policy shows up in the project configuration but MR gating does not function.

Steps to reproduce

Create a project, create a branch, create an MR with security scanning
Introduce a security finding into the MR code
Apply a security policy project with a security results policy that blocks on the above finding
See the security results policy applied in the MR project (Security & Compliance > Policies)
Refresh to see the MR blocked without approval
Disassociate the policy project from the MR project
Refresh to see the MR unblocked
Re-associate the same policy project and policy with the MR project
See the security results policy applied in the MR project (Security & Compliance > Policies)
Refresh to see the MR ignore the policy and not block as expected