If your table is based on the Contact object, but the date field is on a related object like Accounts, you would be able to display the date field in the table but not edit it.

That was my fear.  Why is that - and is there a workaround?  It is frustrating that there is no message in the UI to indicate the Action is not going to have any effect…

If you don’t mind editing in a popup, I would: 1) add a model to your page on your related object that you can’t edit inline 2) make your row action “Open popup”, or “open drawer” depending on your taste 3) in the popup (or drawer), add 2 field editors : one for your primary object and one for the related object. 4) add the fields you want to edit to these editors. If you need inline editing: 1) add a UI only field to your primary model and add that field to your table. 2) disable the save button in the table settings 3) add a title component or navigation component or button component above the table. Any of these can be used to make a “button” that can run actions. 4) add an action that updates the value of a field on your related model. Have it set the value of that field to the value of the UI only field in your primary model. 5) add a second action to save the related model 6) add an action to save the primary model This should allow you to edit the field on the UI only field inline, then upon save it will copy that UI only field to the field on the related model, save the changes, then save the rest of the inline changes on your primary model.