ServiceNow Remote Instance Spoke issue

[bonsai]

The same issue as in the article below occurred.

https://www.servicenow.com/community/developer-forum/create-or-update-remote-record-action-uniquenes...

I tried the solution suggested in the article above, but I can't check the checkbox even when I click it.
No errors occurred when using the browser's developer tools.

Does anyone know what the cause might be?

The field in question is a string type custom field.

No special attributes or default values ​​have been set.

[FernandoUrrutia]

(In the article about)The "Determines uniqueness" checkbox is disabled for Create or Update Remote Record actions because your local instance cannot enforce uniqueness on a remote system. If you need this behavior, you should first run a Remote Lookup to check if the record exists, and then use a conditional to either create or update it. Uniqueness must be handled on the target instance (e.g., with unique indexes or business rules). I Believe this is reason...applied to you to?