Not enough contrast in the fabric as others have said. You might try to use your triangles as star points for another try at the technique. Here's what I did with my first try at Kaleidoscope blocks. I used the same size triangle for the all of the quilt except the border and a floating strip across the top and bottom. I whacked off the triangles on the sides to make it straight.
Stack 'n' Whack large hexes
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