I'm late to this thread, but:
my perception has been that the prevailing viewpoint among experienced audiophiles is that a particular strong point of tube amplification tends to be imaging and dimensionality. And that has certainly been my experience, and the experience of several of the others who have responded.
We can only speculate as to why your experience has been the opposite.
The reason solid state can seem to have sharper images in the sound field is due to the fact that generally speaking, solid state amps tend to have less low level detail (the why of this is a topic for a different thread but in a nutshell has to do with how the human ear interacts with the noise floor of the amplifier; if anyone is interested I can go into that in greater detail, if you will pardon the expression).
How this affects imaging is that without as much low level detail, the images in the sound field will seem to be in sharper relief. However upon careful listening you will find that in comparison to most tube amps, the images have a 2D/poster quality, as the air (ambiance) around the individual performers is removed; this makes the images 2D but more distinct.
Add the low level detail and the effect is more like what you find live- that there is ambiance created by the sounds of each instrument that tends to take away the stark relief but also adds a 3D quality, which of course is what it is supposed to be...