I haven't seen this reported before. I have noticed when creating a sheet worker with any _max attribute, it does not create the newValue and previousValue properties. For example, create two inputs, textareas, or spans, one for the normal attribute, and one for the _max attribute < textarea name = "attr_example" ></ textarea > < textarea name = "attr_example_max" ></ textarea > Then create a simple sheet worker on ( 'change:example change:example_max' , event => { console . log ( event ); }) Then enter anything in the example box, both example, and example _max events fire (as normal), but their contents are different: If you enter anything in the _max box, you see the same thing. The lack of a value in the _max box means it is impossible to caclulate the magnitude of changes, or the direction of changes. This is important stuff!
