IOS build getting stuck

I’ve launched an iOS build over 12 hours ago.
It seems to have got stuck, as it is being reported as still running and as a consequence I can not kick off any builds at all:

[exp] Making sure project is set up correctly...
[exp] Your project looks good!
[exp] Checking if current build exists...

[exp] ============
[exp] Build Status
[exp] ============

[exp] iOS: Build in progress...

...>exp ba
[exp] Making sure project is set up correctly...
[exp] Your project looks good!
[exp] Checking if current build exists...

[exp] ============
[exp] Build Status
[exp] ============

[exp] iOS: Build in progress...
[exp] Cannot start new build, as there is a build in progress.

What would be the best way to get the build cancelled?