I tried it again today. I restored roon on my iMac, my edits, play counts and date added were there again. The version is 1.1 build 102. I forced a full rescan and closed roon.
I copied the roon directory via the network to my windows 10 NUC. I saved it as RoonServer and installed roon server again on the NUC.
As the new log-files are saved in the same directory, I assume that the path is correct.
I then deinstalled roon from the iMac and installed it again as a remote. I pointed the data source to the SSD drive in the NUC. It found the music, but all my edits are still gone. It now shows the correct number of albums, in contrarary to yesterday.
I think its the pointing at the SSD that is the problem as this is not setting it as a remote. You should just be able to point it to the existing server.
I think I found my error. When changing the music location from the network drive to the local drive, I disabled the network drive.
I now read, that you have to remove it and now it looks much better. The play counts are there again and recently added shows up correct as well.
@Mark_S regarding deleting the Roon folder from the Mac: I guess I might have forgotten that yesterday, that might explain the double count of the albums.
No problem, happened to me too migrating from Mac -> Windows.
The app uninstall process is somewhat inconsistent between the two OSes because Mac does not offer a prompt to delete the Roon user folder. You have to remember to do it manually.