What exactly do you mean by 'removing the surrounding "Promise" method'? Do you mean removing the entire block of code that runs in the done handler? Because that's a pretty big change that doesn't really have anything to do with promises.

This is a known bug in IE, based on a specific order of DOM operations. You can see that this came up 3 years ago in jQuery UI: http://bugs.jqueryui.com/ticket/6720 and the solution was simply changing the order of the style changes.

This is reproducible even without promises.

When I say “removing the surrounding Promise method”, I am referring to my JSBin sample code. Changing

base.$hideable.promise().done(function(){
    if(!isVisible) {
        $clicked.next('div.hiddenContent').slideDown(300)
    }
})

…to…

if(!isVisible) {
    $clicked.next('div.hiddenContent').slideDown(300)
}

… prevents the problem from happening. Obviously I cannot actually do this, but I thought it might highlight that it was the “Promise” that was causing the error. Clearly this is not the case.

As for the solution, the bug ticket from three years ago states the problem is with the addClass() method, and you say I should change the order of the style changes. As you can see from my provided sample code, I am not using the addClass method. I am simply using slideUp() on multiple elements, followed by a slideDown() within a promise. There isn’t much I can change the order on.

The fact that it exists with .addClass() is irrelevant. It's based on the order of style changes. This can be reproduced without jQuery.

Because we get so many tickets, we often need to return them to the initial reporter for more information. If that person does not reply within 14 days, the ticket will automatically be closed, and that has happened in this case. If you still are interested in pursuing this issue, feel free to add a comment with the requested information and we will be happy to reopen the ticket if it is still valid. Thanks!