Can't Load Google 3D Tiles

I’m trying to run Cesium for Unity on Ubuntu, despite the lack of support for Linux it’s mostly worked. I’ve been following the dev setup instructions (cesium-unity/Documentation~/ at main · CesiumGS/cesium-unity · GitHub) and have almost everything working, I have Cesium running in Unity on Ubuntu and can use Cesium World Terrain and the Cesium OSM Buildings, but when I try to use the Google Photorealistic 3D Tiles I get the following error:

[error] [TilesetJsonLoader.cpp:696] Error when parsing tileset JSON, error code 3 at byte offset 0

UnityEngine.Debug:Log (object)
Reinterop.ReinteropInitializer:UnityEngine_Debug_CallLog_FA05wu8x__otZNsgdHTnU9A (intptr) (at Reinterop/Reinterop.RoslynSourceGenerator/ReinteropInitializer.cs:13140)
Reinterop.ReinteropInitializer/ActionNativeFunction:Invoke () (at Reinterop/Reinterop.RoslynSourceGenerator/ReinteropInitializer.cs:9866)
System.Threading._ThreadPoolWaitCallback:PerformWaitCallback ()

I have double checked that the token I’m using is valid and allows access to the Google tileset, any ideas on what’s causing this error or how to fix it?