Migrating from FreeNAS 11.2 to TrueNAS

I’ve now transferred the dataset from the backup to the main drive. Now I’m trying to set up an SMB share where all the snapshots are also accessible. I can access the drive from a Windows computer, but I can’t access the snapshots under “Previous Versions.” I can’t select “Enable Shadow Copies” in the options. It’s selected, but grayed out. I can’t add any options under “Advanced.” What could be causing this?