This is a known issue on Xiaomi cell phones.
The call comes in and does not show the Caller ID. Only when the call is terminated does it show the caller ID, which does not help if you’re getting many spam calls.
There is a good article at Truecaller Support, but the Android version they demonstrate their solution on is not the same as the one we had on our phone. Their article date is 2014, so their Android version must have been a lot older. We have Android 5.1.1 loaded on our device.
Tap on “Settings”.
Under the “Device” section (right at the bottom) tap on “Installed Apps”.
Tap on “Truecaller”.
Tap on Auto “Show Notifications”. It is the Floating Notifications we want to activate.
Activate “Floating Notifications”.
Please leave a comment to tell us if this worked for you.