Hello there,
Have you indexed to search the Network drive?
I suggest that you try to index the sub folders manually on the search Index and check if you are able to search through the network drive.
a. Click on Start and type search index in the search field.
b. Click on ‘Change how Windows searches’.
c. Click on Modify and go to the location. Include the sub directories and check if you have the same issue.
Windows Search does not work in a DFS environment (Distributed File System). If you use DFS shares on your network, you'll need to change your workstations so that they map directly to the server where Windows Search is set up.
I hope this information helps. If you have any questions please let me know and I will be glad to help you out.
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