Just received a call from WD.
So apparently there is a maximum of 5 when used in hardware RAID array.
I am the first person ever to use more than 5 outside of hardware RAID that has ever called WD for this issue. They gave me a case number and have asked me to call back on Monday. I will have our main builder call on Monday for a "Tier 2" level support call.
I did ask them if anyone has called for any reason that had more than 5 RED drives connected via motherboard and he said that he (or others who were helping him troubleshoot this issue) and he said he didn't think so.
So stay tuned.