I think it's not the device, it's the iOS. Cause I have three iPads, one of them is too old to be updated to iOS 10, that's the only one that can still do the recording function. My other two iPads' iOS are up to date, and neither of them work. If your iPads have iOS under 10, then just never update it!
PS. I just saw that you said your iPad is not compatible with iOS 10. Great! Use only that iPad