Your heel corner is close to the stabilizer, and you have hone wear over the stabilizer and on the stabilizer. Honing on the stabilizer will keep the edge off the stone and you could be keeping half of the edge from making full contact.
If you go to a Ark the edge must be already refined (at least a good 8K)as they cut/polish slowly, or do a lot of laps.
Reshaping the heel will move the corner further from the stabilizer and prevent riding on to the shoulder. Don’t be afraid to use more pressure with an Ark and lighten up for finish strokes.
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