Indeed, the eviction is working. The problem is the IOException. The IOException is caused by the filesystem (NFS/CIFS) un-mount and re-mount, but FilleCacheStore is not aware of the change underneath. See other thread on "No such device" exception.
Normally the file cache store is recommended for local use only, and if you wanna have a shared file cache store, you'd better off using a JDBC database based cache store.
However, I think your use case is not far fetched, and we're indeed working on a redesign of the file cache store.
So, I'd suggest adding your use case to https://community.jboss.org/docs/DOC-17859 so that it's taken into account when redesigning it. That is, to support NFS access with re-mount operations.