Extending published datasets blocked

A SOL user reported that they can no longer add data to an already published dataset. They get a 422 error message, saying "DatasetType.owned is not a value of this enumeration." with error type "value_error.exception". See the added screenshot for how this renders in the front-end.

Edit: this issue is only reproducible with older published datasets, and does NOT apply to newer published datasets. This was first pointed out by @ahmil, and later on traced by @thchang and myself. Below is a screenshot from Mongo Express that shows how in the column dataset_type

• old datasets have the incorrect value "DatasetType.owned".
• new datasets have the correct value "owned". Note that in the Python code base, these values are the attribute name and value, respectively.