You do not give model / part numbers. However, with our 2007 RV-8, the Vans instructions were clear you will not get to the 'low RPM' Governor stop (nor realistically do you need to).
In addition, to get Prop to drop RPM, you'll often need 1500RPM+, and on a new engine installation, it can be reluctant to move early on, presumably until oil has got through the system.
NB also the engine break-in instructions often cautioning against RPM cycling to any major degree. I personally on a ground test just look for the slightest hint the blades will start to move and then do rest as part of normal pre-flight checks.
