There is a complex interplay of camera type, camera firmware version, FCP version and Atomos Ninja V firmware version to make that work. It differs with each camera. E.g, on the Sony A7SIII, RAW ISO metadata was reported starting with Ninja V firmware 10.55, which also required a camera firmware update to version 1.02, and beginning with FCP 10.4.9.
However RAW WB and ISO metadata adjustment did not start working for the A7SIII until Ninja V firmware 10.64. It did not start working for the Sony FX6 and FX9 on the Ninja V until Ninja V firmware 10.65. WB and ISO adjustment for ProRes RAW from the Sony cameras on the Shogun 7 recorder, although it could technically record ProRes RAW.
For many Ninja V SKUs, you have to purchase a separate license for ProRes RAW or it won't work. Some of the camera and recorder combinations have separate ProRes RAW licenses for HDMI vs SDI. It is very complex and confusing.
In general I'd recommend upgrading your Ninja V to the latest firmware version and trying that. For material already recorded, you can examine what version of Atomos firmware was used to create the ProRes RAW file by using a metadata viewing tool like Invisor or MediaInfo. Comparing that to various Atomos Release Notes for the firmware versions may give some idea about whether WB and ISO adjustment is supported in post for the given camera type, camera firmware, and Ninja V firmware.
You can also verify it is ProRes RAW, not regular ProRes 422. The easiest way is play it in Quicktime Player and do CMD+I.