Disappearing albums

Roon 1.1 (build 65)
MacBook Pro (15-inch, 2.53GHz, Mid 2009)
OS 10.11
Library on Synology DS213, ethernet connection

I’ve experienced a phenomenon about 4 times over the last few weeks. In the middle of listening to an album Roon will stop playing in the middle of the song. When I check Roon it says album has disappeared (although it still exists in my watched folder.) When I go to Overview all of my albums are disappearing and the count goes all the way down to 0. When I restart Roon it will rescan the library and find it (though this takes awhile with 3500+ albums).

This happened twice within an hour this evening. Unfortunately, when this happened to the second album I was playing, it then completely disappeared and is no longer in my watched folder.