I just raised a bug report over here: <a href="https://app.roll20.net/forum/permalink/11384819/" rel="nofollow">https://app.roll20.net/forum/permalink/11384819/</a> . My past history with that forum has trained me to be caututious with expectations, , so I'm asking here, has anyone seen anything like this and do you know a workaround? For the record, here's the full post: 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 &lt; textarea name = "attr_example" &gt;&lt;/ textarea &gt; &lt; textarea name = "attr_example_max" &gt;&lt;/ textarea &gt; Then create a simple sheet worker on ( 'change:example change:example_max' , event =&gt; { &nbsp; &nbsp; console . log ( event ); }) Then enter anything in the example box, both example, and examplee_max events fire (as normal), but their contents are different: If you enter anything in the _max, you see the same thing. The lack of a value in the _max box means it is impossible to caclulate the magnitute of changes, or the direction of changes. This is important stuff!