Logos has been sitting at "Preparing your library" for 20 minutes, without doing anything. In the end I closed it. Here are the logs:
8032.Logos.log
4426.LogosIndexer.log
The last time I used Logos it downloaded and indexed some Vyrso books. I'm attaching the apparently successful log from that operation, in case that's useful:
1581.LogosIndexer.log
To get it working again I had to kill the indexer, and after that it successfully loaded:
73014.Logos.log
6180.LogosIndexer.log