Try this - instead of disconnecting and reconnecting the hosts, just log into the host using Putty/SSH and run the following command:
#services.sh restart
If that does not fix the issue, try logging into the Virtual Center Server machine, opening services.msc and restart the VMware Virtual Center service and see.
Either of those will help.
If restarting the services.sh helps, it would be a host issue. However, I think you might be running into the Virtual Center issue that is documented in the following KB
http://kb.vmware.com/kb/2020277
To verify if you are hitting this, on the Virtual Center machine, go to C:\ProgramData\VMware\Infrastructure\VMware VirtualCenter\logs\
There would be a bunch of files starting with vpxd*.log
Use Winrar or 7zip to extract the files and search for "not collecting stats"
Regards
a