Does the problem go away if you disablePreview new features?
Has this ever worked for this form view?
Are you adding, or editing the row when the error occurs?
Does the form view have a Form Saved event action? If so, please post a screenshot of the action’s configuration.
Is the form view on a slice? If so, post screenshots of the slice’s configuration and its Row filter condition expression.
Let’s start with that. If that’s not enough, continue below.
Please post screenshots of all configuration that supports this limitation, such as the table’s Are updates allowed? expression and the Editable? (Editable_If) expressions of the involved columns.
Please post screenshots of:
The key column’s configuration.
The key column’s App formula expression.
The form view’s configuration.
Are any of the 4 columns used by the key being changed within the form view?
Are any of the 4 columns themselves virtual columns?