My 5yo who is very verbal is not yet reading. He has some visual issues though, and is probably a candidate for vision therapy with a developmental optometrist. My suspicion is these visual issues are why he's not yet reading.
Not all HG+ kids read early though. Some start at a more or less "normal" time or even late. It's not unusual for these later bloomers to go from easy readers to Harry Potter in a matter of weeks.
Does the test score ring true to you beyond the reading issue?
I'd advise that testing is merely a tool to help you understand your child. It shouldn't be substituted for your own observations or "gut" sense about your child.
