TextureImporter and AssetDatabase.ImportAsset

Hello. As part of an AssetBundle build process I want to modify the maxTextureSize of textures at runtime.

I've searched for how to do this, and found a few examples, but my code doesn't seem to work:

 Texture2D tex = (Texture2D)material.mainTexture;
      
 string texPath = AssetDatabase.GetAssetPath( tex );
 TextureImporter textureImporter = (TextureImporter)AssetImporter.GetAtPath( texPath );
                
 textureImporter.maxTextureSize = 512;
                
 AssetDatabase.ImportAsset( texPath, ImportAssetOptions.ForceSynchronousImport | ImportAssetOptions.ForceUpdate );
                    
 int stophere = 1;

I would have expected that if I put a breakpoint on the "int stophere = 1" and view tex.width and tex.height in the watch window I would see the effects of the re-import.

Is this an incorrect assumption? Thanks in advance.