When a datastore is extended through a single host UI client, rather than through vCenter, only the host where the datastore was extended is aware of the new size. vCenter will randomly select a host connected to the datastore to query the size information, so if there are multiple hosts connected vCenter may query one of the hosts that is unaware of this change
6.0
7.0
8.0
Rescan storage across all hosts connected to the datastore, whether via individual host UI clients, or through vCenter by following the documentation or KB links below: