I had a similar issue but not sure if it’s related. You can try two different things…
First, you can try “unique”: “false” for the field you’re having a problem with. I had to do this in my case. To find out more from your error, you can find verbose error information in the Chrome Web Dev tools on the front end in your dev environment. It’s actually been very helpful over time to see what error data can come across through the dev environment.
Hope it helps!