Json field not transmitted

I created a sample project on my end with a table matching the model you sent, but I still can’t reproduce the issue.
Both create and update work.

The difference I have is that I only kept the console.log call in the validator function.

Maybe this is not related, but we had an issue yesterday requiring some users to refresh their visualisation. Saying restarting you local environment fix the issue might be an hint.
Could you please follow these steps to try it?