Maybe I'm making something wrong but, Import symbology doesn't work like in arcmap.
I find that importing symbology destroy at the same time the labeling with the labeling of the import layer. I just want the symbol updated not touching other parts of my layer.
No, passing symbology from a layer or layer file give the same result.
Could be a bug. Search for it here:
https://support.esri.com/en/Search-Results#search?q=arcgis-pro&content-type=Bugs