If I were you I would troubleshoot as follows: 1. Verify you can load the record in the UI 2. Verify if you can replicate the issue in another environment (other sandbox or prod -- your call, but it's just record load so should be safe) 3. If you can replicate the issue in another environment, try disabling other scripts running on the record type (scripted records) and see if the issue persists. No idea if other scripts would be a root cause, but I feel this would rule out the concern.