I'm not aware of these issues, but I have to tell that I've been looking for a substitute with no success. Every plugin have their own issues, I've been thinking in start developing a new one, but to be honest I have no time available for this new project.
Till Kruss Nginx-Cache plugin does not support WP multisite, this issue have been reported several times by users and the author seems like don't care about it.
We need to find a substitute soon!