Material errors when importing obj without materials

Using this code to import an obj file:

var sourcePath = Path.Combine("C:\\Users\\***\\Desktop\\universal_robots_ur5e\\assets\\", Pfile);
var outputPath = Path.Combine(Globals.ProjectContentFolder,"MuJoCoEd\\Models");
var outputLocation = (ContentFolder)Editor.Instance.ContentDatabase.Find(outputPath);

var settings = new FlaxEditor.Content.Import.ModelImportSettings();
settings.Settings.ImportVertexColors = false;
settings.Settings.ImportMaterials = false;
settings.Settings.ImportMaterialsAsInstances = false;
settings.Settings.Scale = 1.0f;

Editor.Instance.ContentImporting.Import(sourcePath, outputLocation, true, settings);

Generates a lot of output log content like this:
[Assimp]: Info, T3000: OBJ: Opening fallback material file C:\Users//Desktop/universal_robots_ur5e/assets/wrist3.mtl
[Assimp]: Error, T3000: OBJ: Unable to locate fallback material file C:\Users/
/Desktop/universal_robots_ur5e/assets/wrist3.mtl
[Assimp]: Error, T3000: OBJ: failed to locate material LinkGrey.002, creating new material
[Info] [Assimp]: Error, T3000: OBJ: No object detected to attach a new mesh instance.

I will be assigning a material to it later and the asset is not immediately attached to an actor… The use of a temporary material is OK, but how can I suppress the Error messages or handle this more cleanly?

Edit: I have tested with with skip settings = false (third argument for the import), but it still tries to import the mats.