AGS community: Cannot create custom metadata.

[AbdoNetGeo]

Hello all, 

I'v deployed the latest govrenance community; 3.5.a to Docker.

I created a Records Managment site, and was following the guide provided in docs.alfresco.com (Custom Metadata)

I keep having this message:

"We couldn't add new custom property 07030009 Could not parse JSON from req.. Contact your I.T. Dept."

In the logs:

Caused by: org.json.JSONException: JSONObject["mandatory"] is not a string.

Log File 

Thanks.