When attempting to add datastore's to a storage profile within VRA 8.6.2 not all of the expected datastore objects are visible. The same datastore are visible in the vRA UI under Resources > Storage
Not having SDRS enabled on the datastore clusters in vCenter Server can also cause this symptom so as a first step validate the SDRS setting of the missing datastore cluster in vCenter.
Only the UI is affected by the issue.
In scenarios where creating the storage profile is urgent and upgrade is not an attractive option the IaaS Api can be used to create the storage profile.