Cannot enable Argo

I cannot enable Argo, despite having subscribed and paid for it.
It worked fine until now, but now it won’t switch on.
I get a message informing me to turn it on, but when I enable it, it turns off again.
I note this has been reported before, but it couldn’t be reproduced. Regardless, it is 100% happening on my instance of Cloudflare.
Can anyone help?