Make sure the mappings and visibility are set properly in the storage management configuration utility for your SAN.
In my case, default mappings had been configured for some volumes and not others.
Explicit mappings for the remaining volumes had been created (by someone else) for two of the hosts but not the third new host that I had just installed.
This created an abundance of confusion, since the storage configuration was expected to be consistent.
Adding explicit mappings for this host did not solve the problem for some reason unknown to me, but reconfiguring the volumes with a default mapping did.