We wanted to test advanced list custom field configuration
However whatever settings we use in the option, we get a 500 error on display as "Your customfield configuration is not correct. The json string that you've entered in the field options is malformed"
We tried VALUE=LABEL with or without quotes, on several lines, separated by commas etc etc
Could you check ? all other fields types are ok
Also can you tell me whether these custom fields are correctly sent by the API endpoint ?