To be honest...I dont know for sure... but I think it does. You would think the high level stuff would just filter down wouldnt you....but have you noticed how sometimes you erase detail at one level, and evidence of it is still there at others? And it stands to reason doesnt it...otherwise you wouldnt have the levels in between, and all the manuals would just say...'import your mesh...divide it as much as you can......and sculpt.'

My hunch is that this is maybe more the reason... not a technical issue...but a 'process/workflow' issue....

...but thats just a hunch. I cant think of any other reason, other than if you have used the wrong settings on exporting your normal map/obj...but you seem to be on top of those and aware of most of the other common solutions...

Did you work almost exclusively at the highest sub-d level?