I've got a razor which I'm having difficulty honing. The heel and toe have taken a good bevel, but there is an inch or so in the middle which won't get to a decent sharpness (judging by AHT - TNT feels the same all along.)

There is no spine wear, and no smile or frown, on a full hollow 5/8 Shumate razor. The sides of the bevel area are the same width all along the blade, and the same width on both sides.

Using a magic marker, it seems to be making contact evenly all along the edge, and looking at the tape after peeling it off the spine, there is even tape-wear from heel to toe on both sides.

I'm using a King 1k (freshly lapped) to set the bevel, and I've tried circles and x-strokes.

Any idea what might be causing the problem, and suggestions for solving it?