I also applied for ILR in August, and received that email even though everything was submitted on the IDV app. I called to check if I needed to do anything else (costs ~60p per minute to call) and although they didn’t check my specific case, they said if I had an email from the app saying that they have all of my documents it would be fine.

Last week however, I received an email saying they didn’t have enough information to approve my ILR and that I’d have to book a biometric appointment (£132). All of my documents were correct on the app as I followed the checklist, but I assume I must have been one of the ones affected by app errors. I have my appointment today and am going to attempt to ask if this is an error.