Hi there...
I just wanted to jump on the thread to explain exactly what is happening here and why clearing your cache is the only option at the moment for this menu appearing.
Whenever we release an update to the site to change functionality there are some CSS and Javascript files that get updated. These files are responsible for how the site looks, and for any interactions that can happen on the site without needing a page refresh (for example, toggling the menu on mobile).
In order to increase performance, we send these files through with an expiration date far into the future so that your browser is able to cache them indefinitely. That means that when you come to the site you don't have to re-download the files after the first time they have been downloaded. This presents a problem when the files have actually changed, because the browser doesn't re-download the files to check.
In order to work around this, when something has actually changed in these files we tell the browser by adding a version identifier to the address that the file is requested from. This is an industry-standard practice that most sites use and the version identifier gets automatically updated every time the files have changed.
On two occasions in the last few weeks we've seen some browsers completely ignore the version identifier and not download the newest versions of the files. This causes a mismatch in the on-site functionality and those files. In this specific case, the result of this mismatch is that the menu loads in its open state and cannot be closed.
We're currently investigating why a small subset of browsers are ignoring the version identifier and we're actively testing multiple configurations on a large range of devices and browsers.
What this means, in practical terms, is that browsers that are not seeing the newest files need to be forced into doing so. That's not something we're able to control from our end - especially if they're ignoring our version identifier - which is why clearing the cache in the browser fixes the problem. It's also why looking at the site through FaceBook fixes the problem, and why viewing the site in an Incognito / Private tab works - they're essentially browsers that haven't downloaded the files before so they get the newest versions correctly.
@swg1 I also wanted to assure you that all the changes that are released to the site are tested in multiple browsers using a cross-browser testing tool, both on test versions of the site and on the live version of the site once they have been released. However, these tools don't show this problem because every test run loads a brand new version of the browser which downloads the newest versions of the files correctly.
I understand how frustrating this can be, and I wanted to assure you that we're trying to find the root cause of this problem and will roll out a fix as soon as we can.
Thanks