Unable to set a simple array condition using the interface

I wanted to set a Condition based upon the selection within a Drop-Down Menu. This is the Drop-Down Menu…

And here is the html as seen in DevTools…

If I enter things manually, like this, it works well…

dmx-bind:condition="[1,9].contains(select1.selectedValue.toNumber())"

But using the Bindings interface, things fail.

Here it is hand-coded in the Code view…

But this is how the same thing shows in Design view…

And this is what happens when you try to use the Data Formats panel, and the subsequent Error Notification…

I cannot set it in the Data Bindings panel. Is this an error or am I doing it wrong?