I have this trouble too(https://developercenter.vmware.com/forums?id=4103#532942|3240352). After update vrop from 6.0 to 6.2, vrops did not receive any data from my vcenter (5.5).
I Remove and Re-Add Adapter Instance, collecting data has started, but all my data has gone.
Check box to remove all related object data was unchecked, but after i re-add the adapter, all objects and historical data was deleted..
How i can take back my collected data?
My recommendation is open a SR on support VMware to fix it.