High Sierra's Finder don't index files in storage unit
I am not sure whether you have tried this or not. I would suggest running the following command on Terminal to enhance the feature of SMB first. 

Speed up browsing on network shares

defaults write com.apple.desktopservices DSDontWriteNetworkStores -bool TRUE


Force the Finder to gather all metadata first

defaults write com.apple.desktopservices UseBareEnumeration -bool FALSE


Logout and login back from your Mac machine, and give a try to find the files from your SMB Shared Network.