As far as I can see.
The layer is on in both viewports.
The drawing has been regen'd multiple times.
The second viewport was a direct copy of the first (just used pan to create a new centre)
Is the second viewport clipped?
I'm not at work at the moment, so I'll look when I'm in tomorrow, I'd not thought about that.
I can see all the information, but this block is just in the wrong place in only one of the viewports
Its been one of those days where I've spent more time sorting out problems than doing cad drawings. Its probably something real simple...but my brains gone.
Oh well, tomorrows another day