Like many people I am also using an Apple device and an Android device simultaneously and facing the problem of some contacts not available on either of the device.
For Example: If you save a contact on Apple it is not available on Android device or vice versa.
The basic cause of this problem is the information not being exchanged between your device and the online account (google or apple) in which you are writing the information. If in your apple device the information is being written on ICloud/Apple account it won't be available on Google platform like Gmail or Google contacts. On the other hand if you save the information on Google account on your iOS device it will be available on your iOS device and android device.
But the same google account should be used on both the devices, like if you are using
