Could you have put the block on the wrong layer?
Good thought with normal AutoCAD Greg, but there are at least 3 different places in Civil 3d where these layers are specified or affected by a parent entity and usually at least one of them specifies Layer 0 as a target. The program puts the object seemingly on whichever of these settings it thinks has the highest rank - usually the most inconvenient one for manipulation.
Freezing layers in Civil 3D seems to have some
surprising results at times. OFF seems to act more like I would expect, but I think it is best to make the change in the Layer dialog rather than by a pick. I have found freezing or turning off by pick to be particularly problematic. Individual items can be nested down 2 or more layers depending on your default settings and it seems more than half the time I will wind up freezing layer 0 or find out that I already have done so.
I'm having a hard time duplicating this, Mark. Using the default settings in the _autodesk civil 3d (imperial) ncs extended.dwt template, I have my trees show a Tree block on layer V-NODE-TREE, the default setting for the label is on the same layer so I changed that to V-NODE-TEXT. I then froze the V-NODE-TEXT layer and my tree blocks are still quite visible.
I think the real culprit may be the default layer Mark has for point creation or for his point group. I have had all kind of interference with these layer settings.
Straying from the default settings for these layer names seems to be asking for this kind of problem.