I created an iterative model in model builder and the .lyrx symbology isn't being applied to the layer. I can batch iterate the layers in my map but when I save and close the map... the updated symbology is not saved in the project. When I save and then open the project, the symbology has reverted back to the symbols that appeared before the batch import. This is a bug.
The only way I am able to apply the .lyrx symbology for each of the many layers, is to import the .lyrx file for each layer... using this approach the symbology can be saved and the next time I open the project, it has been preserved. I have to do this for many layers, so it isn't an ideal approach.