The same happened to me on Tuesday! I emailed them and they said they would look into it, then yesterday I got an e-mail that said:
'Hello,
Please be advised that we are currently working to solve a technical issue affecting our online testing platform. Once fixed by our service provider, you will receive an email inviting you to take the test. This will not affect the time you have in which to complete the test once sent.
We apologise for any inconvenience caused.
Kind regards,
The Graduate Recruitment Team'
I don't know if my application has been bonked for the same reason as I have a small learning disability that I routinely mention on app forms, but I'm a little relieved that at least someone has gotten an answer! Thanks for posting.