Can't delete or unmount datastore

Getting this error when trying to remove datastores.

" Cannot read the host cache configuration because some other process is modifying it at this time."

We aren't using  an ssd for caching, and I've verified there is nothing listed in the host cache configuration for each host. Is it possible there is a running process that needs to be stopped? We've already seen articles on vsantrace (which we don't use) and deleting the DS directly from the host, but still no dice.

Thanks.