Variables not there if disabled was set and then unset

I have two buttons. The second button can’t be pressed until the first button has already been pressed. So, I’ve created a variable ‘varEnableButton’ with a value of 0. Then, as part of the action on the first button I change the value to 1. I then have a dynamic attribute of Disabled on the second button with the value being varEnableButton == 0. It works perfectly - it’s disabled on page load and then becomes enabled after the first button is clicked.

But, the rest of the action on the second button fails because the variables don’t seem to be accessible anymore. I had a Data Detail containing an ID and use this in the action of the second button. But, that GET variable isn’t there when I click the button (browser console confirms this). If I remove the Disabled attribute then it works perfectly.

Is this a bug? Do I need to go about it a different way?