1: Upon sign up did you or your friend enter the first 0 in your phone number? (eg. 0405 123 123), this can create issues, depending how the contact was originally entered into your phone. The solution is to log out of Mi Vista and set up a new user profile without entering first 0 in your mobile phone number (eg. 405 123 123) this will not cause issues having 2 accounts.
2: Upon setting up your Mi Vista profile, did you or your contact select an incorrect International Country Code (eg +61 for Australia). The solution is to logout of Mi Vista and set up a new user profile with the correct international phone code for your country.
3: Check if your mobile phone or your contacts mobile phone has the minimal requirements to effectively operate the Mi Vista App.
4: Shut down the Mi Vista app completely then re-open it.
5: Check that both you and your friend have each other’s correct contact phone numbers on each other’s phone