Yes, and very happily too. Defender seems to not really care where the files are, as long as there's readable data on a drive mounted somewhere accessible, it's all fair game.
Have you tried setting an excluded zone and include your whole SMB share in it
Did an exclude zone ever worked ?
I remember having to turn off the antivirus because it will happilly ignore my exclude zone (10 years ago)
This is my experience as well, I don't know if I'm doing something wrong or not but exclusions never seem to work, at least when Windows is convinced it has found a severe threat. I have to completely disable Real Time Protection.