I will check with Intel, but as I mentioned, the board monitors are "all green" when I look at the RMM using the web interface.
I can see in the RMM which fans are present and which are not, and those in the system are all spinning at the same RPM.
Adding to the confusion, fans #1-6 all have a fan-A and fan-B, and all 5 existing fans have only fan-A present. So again, I am confused as to why VMware would only complain about fan 5, when 1-4 are exactly the same (I can imagine it complaining the fan-B missing on all 5 slots - that would make sense).