The upshot is that the Mac product's Federal Review flagging that Form 8911 is "available soon" is erroneous. If you proceed, you can e-file (or mail file) successfully. That's what I ended up doing after contacting phone support. The "Employee Tax Experts" ought to have a shared database that reflects the workaround to this Mac product bug. (And Intuit really ought to expedite an update to fix this problem, in order to reduce customer annoyance and product support expense!)
