Help With Windows Search (Indexing Options) 19025 Build

I am trying out a test on build 19025 with Windows search, indexing my drives, however I have come across an issue which may have been present with previous builds.

Under Indexing Options/Modify/Show All Locations - one of my external drives show up, but not the other! Any idea's how to get Windows Search to index it? (It is a Seagate Backup Plus Drive. I have two the same, one shows up one does not)

Thanks

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