2017 V90 Reverse camera

[Power6]

You have most likely installed wrong camera - the one from newer models.
It works like this:
V90 2017 and XC90 2015-2017 have old type of IHU (radio/navi) unit - it does not support direct connection to camera.
In those years - you need a special module which is plugged between IHU and Camera (WAM - Wide angle module - parking cameras)

I am curious, in the -2017 models, have you found if the WAM hardware is the same between rear-only and 360 cam equipped models?