Thanks for pointing this out. This is one of those weird edge case display bugs where a problem crops up after a seemingly innocuous set of steps: only in IE and Edge, only when you export a contact using the Actions menu (as opposed to downloading the vCard from the contact itself) and then only when you complete another action after the download completes. Refresh the page and all is clear. It doesn't happen in any other browser, or in any other scenario. There's no console errors in the browser, there's nothing in the Network tab to indicate a problem....And what's stranger yet: any item that has an action, such as the Availability dropdown, help dropdown and even your username dropdown are all there, just hidden.
As it's such an edge case, and as the functionality is still there, we may have to let it be for the time being since a refresh of the page clears up the issue. In addition, we're making major changes to the interface in SmarterMail 16.x so most of our time is spent cleaning that up and making sure that the functionality is there and working properly. Plus, as the interface is SO different in 16.x, this type of issue won't be present.
That said, we will put the issue in our backlog and hopefully look into it at a later date.