I rip CDs or download files, tag them in iTunes on my laptop, the use iTunes home sharing to transfer from my laptop to the E: drive of the Roon server described above. I would expect the items to show up in the Roon library within a few seconds (always have before), but as far as I can tell, the items NEVER show up in the Roon library unless I manually trigger a rescan via the Roon menu. As mentioned, the files are visible on the E: drive via Windows Explorer or directory listing, but apparently Roon is not “seeing” the new files unless I manually rescan.
As a test would you mind to try the following: instead of using iTunes home sharing just copy/ paste files into the watched folder and check whether they are picked up by Roon ?