Storage Migration Service - Failing Inventory Scan

I'm trying to use Storage Migration Server (latest version) via Windows Admin Center to migrate shares from one source server to one destination server. 

When I add the source server in step 1 (Inventory servers) then click Start Scan to do an inventory, it keeps failing.  The source server is Windows 2012R2. It's on the same LAN as the Orchestrator server.  I won't post the complete event detail, although I can if asked, but I constantly get event 2503 and 2509.  These are generic and don't point to a specific issue or solution.

As a test I have tried putting two other of my servers in there as source servers and it inventories those just fine.  

I'm hoping someone has seen this and resolved it.  I have seen two separate postings with this same issue but neither have been resolved, or at least not updated as resolved with a solution.