I think you’re a little confused, tape is not cheating, nor will not using tape make the edge keener.

Tape is used to protect the spine, especially for novice razor honers who will use too much pressure on low grit stones and needlessly grind away a razor spine.

Tape actually can make a keener edge by increasing the bevel angle.

Most probably your issue is an incomplete, fully set bevel and meeting edge. Look straight down on the edge to see if the bevels are meeting.

Put 2 layers of tape on the spine and do some laps on your 12k. Is your 12k a quality Synthetic or a natural stone of unknown grit?