Mark, where did the paste come from and is it pure Chrome Oxide?

You might try pasting a piece of cardboard, inside of a cereal box. Balsa has some silica naturally in it and many complain of harshness coming off balsa. Several years ago when balsa was all the rage, it was a common complaint, especially if use with pressure.

Cardboard is much smoother and makes a great test substrate for paste. Avoid the temptation to use pressure on the strop.

Use pure Chrome Oxide for best results. 75-100 laps on pure Chrome Oxide should remove any visible stria from the edge and about half-way down the bevel, Run a Q Tip along the edge lightly, you will feel the slightest snag if you have a chip, joint the edge and reset it 10-20 X laps on the 12k.

Another thing you can do is perfect your 12k edge. The slightest swarf on the 12k can damage the edge, and I believe a lot of folks over hone on the 12k. The 12k is an aggressive stone but can be a good polisher. Years ago, I did a post on chip removal with a 12k, it is that aggressive. (12K Chip Removal/Bevel Setting).

When you have a good stria pattern on the 12k and a straight edge, where you would normally stop, joint the edge, strop 20-30 laps on linen, lap the 12k clean and hone 10-20 laps under running water. Strop 10-20 laps on linen and 10-20 on leather. Test shave to see if the edge improves.

You can also take it one step further, add an extra layer of tape, joint the edge, strop on linen and do 3-5 light finish laps under running water. Strop and shave. Then strop on pure Chrome Oxide, linen, leather and shave.