I've had this happen to me. The payment failed and me and the client both received a message saying that the transaction was cancelled for our protection. He tried another couple of times with smaller amounts and had the same problem, then he got a text from his bank asking him to verify that the recent activity was him. As soon as he did that it went through with no problem. I've received a payment of £500 and of £750 and it asked me to confirm a few of my details for security reasons then it cleared instantly. I love cashapp it's a lot more reliable that paypal and as far as I can tell impossible to reverse or cancel like paypal is. Paypal has screwed me over a couple of times so I refuse to use them now.